Efforts to reduce low birth weight and preterm births: A statewide analysis (Virginia)

Efforts to reduce low birth weight and preterm births: A statewide analysis (Virginia) Guy M. Harbert, Jr., MD Charlottesville, Virginia OBJECTIVE: The purpose of this study was to ascertain the influence of evolving obstetric and public health care on the occurrence of low birth weight and preterm birth in a large population. STUDY DESIGN: Birth statistics of 2,049,970 live births (25.1 % nonwhite) and 156,009 low-birth-weight infants (39.8% nonwhite) were analyzed. RESULTS: Between 1967 to 1971 and 1977 to 1981 the incidence of infants weighing :52500 gm declined from 85.5 to 74.4 per 1000 live births. The percentage of 500 to 1500 gm infants delivered at perinatal centers in Virginia increased from 41.8% in 1977 to 1981 to 64.9% in 1987 to 1991. In spite of regionalization, expanded maternity services, and increased use of tocolytic agents the incidence of low-birth-weight infants per 1000 live births in both white and nonwhite populations has remained comparatively stable since 1976, although the percentage of term infants weighing :5 2500 gm has decreased. The incidence per 1000 live births of infants weighing 500 to 1500 gm has not changed statistically in 25 years (Student t test). CONCLUSION: The data challenge the overall effectiveness of current programs, including the use of tocolytic agents, and indicate a need to restructure efforts to reduce low birth weight and preterm births. (AM J OBSTET GVNECOL 1994;171 :329-40.)

Key words: Low birth weight, preterm, perinatal centers, maternity services, tocolytic agents

During the past three decades the incidence of lowbirth-weight (LBW) infants born to residents of the State of Virginia has generally been above the national average. In an effort to reduce this incidence specific goals were set and corrective measures instituted to correct sociologic, economic, and medical factors believed to predispose pregnant women to be delivered of LBW and premature infants. Specifically, the number of maternity clinics sponsored by the state health department and the number of maternity patients seen in these clinics were increased. Other measures were directed at identification of individuals at risk for LBW and preterm infants and to modifY these specific determinants of risk. A Perinatal Service Advisory Board, established by the state in 1980, instituted the concept of regionalization with designation of specific perinatal centers. Special programs for preterm birth risk identification and prevention, as well as other pilot programs, were instituted and the eligibility criteria for From the Division of Maternal-Fetal Medicine, Department of Obstetncs and Gynecology, University of Virginia Health Sciences Center. Presented at the Fifty-sixth Annual Meeting of The South Atlantic Assoczatzon of ObstetriCIans and Gynecologists, Orlando, Flonda, January 15-18, 1994. Repnnt requests: Guy M. Harbert, Jr., MD, Box 387, Umverslty of Virginia Health Sciences Center, Charlottesville, VA 22908. Copyright © 1994 by Mosby-Year Book, Inc. 0002-9378/94 $3.00 + 0 6/6/56554

Medicaid expanded. These efforts were accompanied by increased use of tocolytic drugs in attempts to prevent or suppress pre term labor. All of these measures were felt to be associated with success of some degree, at least at the local level. Several recent publications have concluded that similar special programs and efforts, I, 2 including the use of tocolytic agents,3. 4 have not been effective in the reduction of LBW or pre term births. The various authors have suggested that continued implementation of many of these programs and the continued use of tocolytic agents on a wide-scale basis may not be justified. These conclusions were based on review and meta-analysis of individual reports involving limited populations and a few larger but still limited multicenter collaborative studies. To ascertain whether the evolving concepts of obstetric and public health care have had a beneficial influence on the occurrence of LBW infants and preterm births in a large population, the maternal health and birth statistics for the state of Virginia over a 25 year period from 1967 through 1991 were reviewed and collated. Material and methods

Data for analysis were collected from the records at the Center for Vital Statistics of the Virginia Department of Health. Evaluations made in 1950 to determine

329

330

Harbert

the completeness of data for each state estimated Virginia's reporting to be complete for 98.0% of white births and 95.1 % of the nonwhite population. With the progressive increase of both white (99+% since 1972) and nonwhite (99 + % since 1976) births occurring in hospitals, it is assumed that the reporting now is more nearly complete than before. The white population includes persons reported as Mexican and Puerto Rican and those not specifically designated as nonwhite. The nonwhite population includes black, a reported mixture of black with any other race, and all nonwhite races or mixtures. For birth data white and nonwhite refer to the race of the mother. The counts for live births are considered very accurate, because an interstate exchange of birth certificates provides a count of out-of-state events occurring to Virginia residents. Residential data affect citizens of Virginia regardless of where the event occurred. For events occurring in Virginia the data include Virginians and non-Virginians alike. A live birth is defined as the complete expulsion or extraction from its mother of a product of human conception, irrespective of the duration of pregnancy, which after such expulsion or extraction, breathes or shows other evidence of life as prescribed by the Vital Statistics Laws of Virginia, Chapter 7, Section 32.1249.7. An out-of-wedlock event is one that occurred to a women who was not married to the father of the child at the time of the event and had not been married to him at any time during the preceding 10 months. LBW is a birth for which the weight is ::; 2500 gm (5 pounds 8 ounces), regardless of the period of gestation. A preterm birth is one that occurs before completion of 36 weeks of gestation. Duration of pregnancy is the estimate filed by the accoucheur with the Division of Vital Records. Data were aggregated for 5-year increments and presented as totals, percentages, traditional rates per 1000 estimated population in a specific age group as projected by the Virginia Department of Planning and Budget, or per 1000 to another base, such as total live births. When expressed as an annual rate, the value represents the mean calculated from the rate reported for each year. The SD reflects the variation between years within the 5-year increment. The Student t test was used to determine differences between groups. Statistical significance was set at p < 0.05. Results

During the 25-year period from Jan. 1, 1967, through Dec. 31, 1991, 2,049,970 live births were recorded as resident events for the State of Virginia. The proportion of total live births to nonwhite women

August 1994 Am J Obstet Gynecol

was 25.1% (range 22.3% in 1969 to 27.0% in 1989). This percentage contribution is above the proportional racial distribution for the state female population aged 15 through 44 years, which averaged 20.2% nonwhite (range 17.8% in 1975 to 22.9% in 1989). The number of LBW infants born during this 25-year period was 156,009. Of this population, 39.8% were nonwhite (range 34.3% in 1969 to 44.3% in 1989). Resident LBW rate and total live births with proportions born out of wedlock and receiving prenatal care beginning in the first trimester on the basis of age of mother are tabulated in Table 1. The annual rates are aggregated for 5-year increments. Mean values that differ from the previous 5-year period are marked with asterisks. A decrease in births of LBW infants between 1967 to 1971 and 1987 to 1991 was reflected in all age groups. The largest part of this decrease occurred between 1967 and 1976. After 1976 the incidence of LBW deliveries remained relatively stable. However, there was a 7.1 % increase in LBW infants per 1000 live births born to women age 30 to 34 years old in 1987 to 1991 compared with 1982 to 1986. The difference in the average total number of live births between 5-year increments for the various age groups reflects changes in population distribution. The proportion of total live births born to women < 25 years old decreased an average 18.1% between 1967 to 1971 and 1987 to 1991. A progressive increase in out-of-wedlock births occurred for all age groups. The greatest change was in the group 20 to 24 years old. Those seeking prenatal care during the first trimester increased during the first 15 years of review. By 1977 to 1981 > 95% of patients in all age groups, except for those < 20 years old, sought prenatal care during the first or second trimester. The percentage of women receiving no prenatal care did not change between 1967 to 1971 (1.3% ± 0.2%) and 1987 to 1991 (1.2% ± 0.2%) (t = 0.7905). In general, the education of the mother was a more significant factor than age in seeking prenatal care. Since 1976 only those women completing ~ 12 years of education, regardless of age, sought prenatal care in the first or second trimester of pregnancy over 95% of the time. Even this group had an increase in the percentage receiving no prenatal care during 1987 to 1991. Throughout the period 75.0% ± 1.0% of patients made ~ 10 prenatal visits. This percentage varied between age groups. Only 52.2% ± 2.6% of patients <20 years old and 71.1% ± 0.8% of women 20 to 24 years old fulfilled this criteria. The proportion of women in all age groups > 24 years old making ~ 10 prenatal visits averaged 80.3% ± 1.1%. The number of resident live births and LBW infants per 1000 live births with percentage of the respective

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331

Table I. Annual resident LBW per 1000 live births, live births, percent out of wedlock, and percent beginning care in first trimester by age aggregated for 5-year increments 1967-1971

Age of mother

<20 yr LBW/1000 live births Total live births Out of wedlock (%) First-trimester care (%)t 20-24 yr LBW/I000 live births Total live births Out of wedlock (%) First-trimester care (%)t 25-29 yr LBW/1000 live births Total live births Out of wedlock (%) First-trimester caret 30-34 yr LBW/1000 hve births Total live births Out of wedlock (%) First-trimester care (%)t >34 yr LBW/l 000 live births Total live births Out of wedlock (%) First-trimester care (%)t TOTAL

LBW/l 000 live births Total live births Out of wedlock (%) First-trimester care (%)t

(mean ± SD)

1972-1976

1977-1981

(mean ± SD)

(mean ± SD)

1982-1986

(mean ± SD)

1987-1991

(mean ± SD)

II3.0 15,953 58.5 48.2

± ± ± ±

4.3 394 4.3 1.3

103.4 14,197 70.6 53.0

± ± ± ±

3.5* 930* 3.6* 2.3*

106.9 12,187 83.2 61.5

± ± ± ±

3.0 402* 1.8* 1.6*

101.2 10,676 88.6 58.1

± ± ± ±

3.0* 295* 1.0* 1.3*

101.9 10,941 90.7 58.3

± ± ± ±

2.1 507 1.0* 1.3

80.8 31,388 9.5 65.7

± ± ± ±

3.3 611 0.2 1.3

75.2 24,166 12.6 69.7

± ± ± ±

1.3* 1,224* 1.7* 2.1*

76.0 24,772 19.5 78.4

± ± ± ±

2.0 625 2.1* 1.3*

76.5 25,434 26.3 75.9

± ± ± ±

2.0 297 2.0* 0.9*

75.3 25,583 34.3 73.2

± ± ± ±

1.8 256 2.6* 1.0*

74.2 21,261 4.5 74.0

± ± ± ±

6.2 1,128 0.3 1.2

63.2 20,904 4.9 79.5

± ± ± ±

1.6* 444 0.4 2.0*

62.4 23,367 8.2 86.7

± 1.1 ± 773* ± 1.2* ± 0.8*

63.3 25,919 II.8 86.0

± ± ± ±

0.9 865* 1.0* 0.5

64.0 29,407 15.8 85.1

± ± ± ±

2.4 881 * 1.4* 0.4*

75.8 9,415 4.8 70.9

± ± ± ±

4.4 173 0.3 1.6

66.7 8,910 4.5 77.8

± ± ± ±

4.8* 260* 0.4 2.8*

60.7 12,491 5.5 86.3

± ± ± ±

1.7 1,068* 0.6* 3.3*

60.3 15,872 7.6 88.4

± ± ± ±

1.3 1,060* 0.6* 0.5

64.6 20,511 10.3 85.4

± ± ± ±

1.5* 1,150* 0.8* 1.4*

95.0 5,406 5.9 60.2

± ± ± ±

6.6 628 0.5 3.0

88.0 3,381 6.5 69.8

± ± ± ±

2.4 318* 0.8 2.1*

77.7 3,619 7.3 81.3

± ± ± ±

3.6* 254 0.5 1.7*

72.8 5,628 7.7 85.4

± ± ± ±

4.2 721* 0.6 1.4*

70.0 8,596 9.7 87.7

± ± ± ±

4.6 956* 0.6* 0.3*

85.5 83,425 11.6 65.0

± ± ± ±

3.4 1,388 0.4 1.3

76.8 71,560 14.0 70.3

± ± ± ±

1.4* 1,866* 0.8* 2.5*

74.4 76,439 18.1 79.8

± ± ± ±

0.9* 2,305 1.2* 1.3*

72.2 83,529 21.0 79.7

± ± ± ±

1.1* 2,576 0.9* 0.3

72.1 95,039 25.2 79.8

± ± ± ±

1.1 3,043* 1.8* 0.5

*Statistically different ip < 0.05) from previous 5-year increment. tRecords were begun in 1969.

totals on the basis of race and age of mother are tabulated in Table II. The proportion of LBW infants born to white women decreased 7.5%, with a corresponding increase for nonwhite women. There was a progressive decrease in the proportion of LBW infants born to mothers < 20 years old in both races and in the white population between 20 and 24 years old. The proportion of LBW infants born to nonwhite mothers 20 to 24 years old increased 1.7%, but in women between 25 and 29 years old it essentially doubled. The annual rate of LBW infants born to white mothers progressively decreased between 1967 to 1971 and 1987 to 199 l. The only statistically significant difference in the incidence of LBW between 5-year periods for the nonwhite population was 1972 to 1976 compared with 1967 to 197l. The decrease in incidence in both populations was engendered primarily by a decrease in those infants born in the weight group of 1501 to 2500 gm. The incidence of very-Iow-birth-weight (VLBW) infants, those weighing between 500 and 1500 gm, fluctuated without statistically significant change about an average annual rate for the 25-year period of 8.7 ± 0.6 per 1000 live births for the white population

and 20.6 ± l.2 per 1000 live births for the nonwhite population. The incidence of LBW infants born of multiple gestations averaged 50.9% ± 3.4% for the white population and 62.9% ± 2.9% of the nonwhite population. In 1967 to 1971 plural births accounted for l.8% ± 0.04% of live births and 14.4% ± 0.6% of LBW infants born to the white population. Nonwhite proportions were 2.1 % ± 0.1% oflive births and 11.1% ± 0.7'lc of LBW births. In 1987 to 1991 the proportion of live births resulting from multiple gestations was 2.3% ± 0.09% white and 2.5% ± 0.2% nonwhite. However, the percentage of LBW infants contributed by plural births in the white and nonwhite populations increased to 19.8% ± 0.8% and 17.3% ± l.:3% of the total number of LBW births, respectively. Table III collates total hospital live births, LBW births, and infant deaths < 1 week of age by LBW groups for the six designated perinatal centers, the four regional hospitals with newborn intensive care units, all other hospitals, and the State of Virginia aggregated in 5-year increments for the 15 years from 1977 through 1991. In 1977 to 1981 compared with 1987 to 1991 the

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August 1994 Am J Obstet Gynecol

Table II. Resident live births, percent of total live births, LBW infants per 1000 live births, and percent of total LBW by age of mother and by race aggregated for 5-year increments 1972-1976

1967-1971

Age of mother <20 yr White Nonwhite 20-24 yr White Nonwhite 25-29 yr White Nonwhite 30-34 yr White Nonwhite >34 yr White Nonwhite TOTAL

White Nonwhite

Live births

I

LBW/WOO lIVe birthl

1

LIVe births

1977-1981

LBW/WOO lIVe hlrths

1

LIVe births

LBW/1000 lIVe bIrths

49,474 (11.9%) 30,292 (7.30/0)

150.8 (12.8%)

43,983 (12.30/<) 27,005 (7.5')f)

140A (13.8%)

80.4 (12.8%)

36,784 (9.6%) 24,154 (6.3%)

81.5 (10.5%) 145.5 (12.4%)

124,720 (29.9%) 32,223 (7.7%)

67.7 (23.6%) 130.7 (11.8%)

91,392 (25.5%) 29,441 (8.2%)

61.0 (20.2%) 119.4 (12.8%)

89,079 (23.3%) 34,782 (9.1%)

59.0 (18.5%) 119.8 (14.60/0)

88,941 (21.3%) 17,366 (4.2%)

6.').6 (16.3')f) 117.9 (5.7%)

87,666 (24.5%) 16,855 (4.7%)

55.3 (17.6%) 103.9 (6.4%)

92,721 (24.2%) 24,117 (6.3%)

53.0 (17.3%) 98.4 (8.3%)

37,679 (9.0%) 9,398 (2.3%)

66.0 (7.0%) 115.2 (3.0')f)

36,797 (10.2%) 7,726 (2.2%)

58.0 (7.8%) 107.8 (3.0%)

51,501 (13.5%) 10,958 (2.8'!f)

53.0 (9.6%) 97.1 (3.7%)

20,333 6,701 417,127 321,147 95,980

89.7 (12A%)

(4.9%) (1.6%)

82.2 133.9 35,674 71.2 133.4

(77.0%) (23.00/0)

(4.6%) (2.5%) (64.1%) (35.9%)

12,946 3,962 357,803 272,784 85,109

(3.60/<) (1.1%) (76.2%) (23.8%)

76.2 129.5 27.479 62.6 122.2

(3.6%) (1.8'!f) (62.1%) (37.9%)

14,101 3,998 382,195 284,186 98,009

(3.7%) (1.0'!f) (74.4%) (25.6%)

66.4 117.6 28,431 59.2 118.2

(3.3%) (1.6%) (59.2%) (40.8%)

Table III. Hospital live births, percent of total live births, infant deaths at < 1 week, and percent deaths of live births by birth weight according to hospitals of birth aggregated for 5-year increments 1977-1981

Place of birth

Births (No.)

I

1982-1986

Deaths (No.)

Births (No.)

Perinatal centers (6) 2001-2500 gm 5,015 (29.2%) 52 (11.0%) 6,142 (34.0%) 1501-2000 gm 1,947 (37.4%) 69 (3.5%) 2,638 (49.2%) 500-1500 gm 1,851 (41.8%) 541 (29.2%) 2,755 (56.3%) Total LBW 8,699 (30.6%) 851 (9.8%) 11.571 (38.4%) Total deliveries 85,169 (22.3'!f) 989 (1.2%) 101,982 (24.4%) Regional hospitals (4) 1,221 (7.1%) 2001-2500 gm 8 (0.7%) 1,725 (9.6%) 1501-2000 gm 354 (6.8%) 15 (1.4%) 460 (8.6%) 500-1500 gm 286 (6.5%) 90 (31.5%) 322 (6.6%) Total LBW 1,886 (6.6%) 149 (7.9%) 2,568 (8.5%) Total deliveries 31,152 (8.2%) 190 (0.3%) 45,595 (10.9%) Other hospitals 2001-2500 gm 10,936 (63.7'!f) 142 (1.3%) 10,172 (56.4%) 1501-2000 gm 2,900 (55.8%) 161 (5.6%) 2,258 (42.2%) 500-1500 gm 2,286 (51.7%) 848 (36.8%) 1,819 (37.2'!f') Total LBW 17,846 (62.8%) 1,451 (8.1%) 16,002 (53.1%) Total deliverIes 265,874 (69.6%) 2,157 (0.8%) 270,071 (64.7%) State of Virginia 2001-2500 gm 17,172 [44.9]* 202 (1.2%) 18,D38 [43.2) 5,201 (13.6) 1501-2000 gm 245 (4.7%) 5,356 [12.8) 500-1500 gm 4,423 [11.6) 1,479 (33.4%) 4,896 [11. 7] Total LBW 28,431 [74.4] 2,457 (8.6%) 30,161 [72.2] Total deliveries 382,195 3,336 (0.9%) 417,618

I

1987-1991

Deaths (No.)

53 90 592 959 1,109 16 13 84 202 244

Births (No.)

1

Deaths (No.)

(0.9%) 7,316 (3.4%) 3,330 (21.5%) 3,695 (8.3%) 14,736 (1.1%) 124,431

(35.6%) 45 (0.6%) (52.9%) 57 (1.7%) (64.9'!f) 574 (15.5%) (43.0%) 1,043 (7.1%) (26.2%) 1,173 (0.9%)

(0.9%) (2.8%) (26.1%) (7.9%) (0.5%)

(10.6%) (10.5%) (8.3%) (10.4%) (12.8%)

2,178 664 474 3,555 61,005

12 17 94 220 263

(0.6%) (2.6%) (19.8%) (6.2%) (0.4%)

76 56 572 1,068 1,422

(0.8%) 11,047 (2.5%) 2,272 (31.4%) 1,521 (6.7%) 15,994 (0.5%) 289,761

(53.8%) 57 (36.1'!f) 47 (26.7%) 409 (46.6%) 943 (61.0%) 1,163

(0.5%) (2.1%) (26.9%) (5.9%) (0.40/0)

145 159 1,248 2,227 2,775

(0.8%) 20,541 (3.0%) 6,266 (25.5%) 5.690 (7.4%) 34,285 (0.7%) 475,197

[43.2] (13.1) [12.0] [72.1]

(0.6%) (1.9%) (18.9%) (6.4%) (0.6%)

114 121 1,077 2,206 2,599

*Brackets indicate incidence of LBW per 1000 live births by weight.

proportion of total births occurring in Virginia that were delivered at the six perinatal referral centers increased 17.5%, whereas the percentage of LBW infants increased 40.5%. The proportion ofVLBW infants weighing between 500 and 1500 gm delivered in peri·

natal centers increased from 41.8% to 64.9% of total VLBW infants born in the state. The four regional hospitals with newborn intensive care units, including one developing a maternal-fetal obstetric service, experienced an increase in total deliv-

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Volume 171, Number 2 Am J Obstet Gynecol

1982-1986

1987-1991

Live births

LBW/lOOO lzve baths

Live births

LBW/JUOO live hirths

31,390 (7.5%) 21,990 (5.2O/C)

78,3 (8.1'l{) 134.2 (9.8'l{)

31,250 (6.6%) 23,455 (4.9%)

78.2 (7.1%) 134.2 (9.2%)

90,414 (21.6%) 36,758 (8.8%)

59.1 (17.7) 119.0 (14.5%)

86,548 (18.2%) 41,367 (8.7%)

578 (146o/c) 111.8 (13.5'l{)

101,260 (24.2%) 28,335 (6.8%)

51.5 (17.3%) 105.3 (8.8'1c)

112,706 (23.7%) 34,332 (7.2%)

50.1 (16.5o/c) 109.5 (J 0.9'1r)

64,500 (15.4%) 14,860 (3.6%)

50.3 (10.7%) 104.1 (5.1O/C)

82,055 (17.2%) 20,504 (4.3%)

52.0 (12.4o/c) 115.1 (6.9%)

22,781 5,460 417,648 310,345 107,303

(5.4%) (1.3%) (74.3%) (25.7%)

333

62.0 114.6 301,62 57.0 116.3

(4.7O/C) (2.0%) (58.6%) (41.4%)

eries, as well as the LBW groups proportionate to the increased population in their areas. A significant decrease in the death rate of infants < 1 week old occurred for all weight groups between 1977 to 1981 and 1987 to 1991. Infants weighing ~ 1501 gm did not experience a significant difference in survival rate regardless of place of birth. However, those infants weighing 500 to 1500 gm born in the six perinatal centers experienced a survival rate 4.2% higher than those born in the four regional hospitals and 1l.9% higher than those born in other hospital facilities. Table N presents age-specific rates of resident singleton live births per 1000 females subdivided by race and age of the mother with the percent out of wedlock for both full weight (> 2500 gm birth weight) and LBW infants and LBW births per 1000 live births. Although most of the age groups experienced a statistically significant decrease in the annual rate of LBW infants per 1000 live births between 1977 to 1981 and 1987 to 1991, there was less progress after 1981. Only white women 25 to 29 years old demonstrated a statistically significant decrease in the incidence of LBW infants between 1982 to 1986 and 1987 to 1991. The nonwhite population in both the 25 to 29 and the 30 to 34 year old groups experienced a statistically significant increase in LBW incidence between 1977 to 1981 and 1987 to 1991. Out-of-wedlock births increased in the white and the nonwhite population in all age groups for both full weight and LBW infants. In all instances the highest percentages were recorded in 1987 to 1991. The proportion of LBW infants born out of wedlock was con-

34,703 8,277 475.197 347,262 127,935

(7.3%) (1.7%) (73.1%) (26.9%)

58.3 118.3 34,263 55.8 116.3

(5.9%) (2.8%) (56.6'7c) (43.-1%)

sistently greater than the percentage for the full weight populations. The greatest differential in out-of-wedlock status between LBW and full weight pregnancies in 1987 to 1991 was in the 20 to 24 year old group for the white population and > 34 years old for the nonwhite population. Only for those patients < 20 years old was the differential not statistically significant. There was less differential between women delivered of LBW infants and the full weight population in the percentage beginning prenatal care in the first trimester of pregnancy. Under the age of 25 years 63.1% ± 6.1% of women delivered of LBW infants received first-trimester care compared with 67.6% ± 8.5% for the full weight population (t = 0.9617). The percentages for women ~ 25 years old was 74.0% ± 3.7% versus 85.8% ± 1.9o/c, respectively (t = 6.3437, P < 0.01). A similar disparate relationship existed between the white and nonwhite populations giving birth to LBW infants. Under age 25 yean the 67.9% ± 7.0% of the white population and the 58.2% ± 6.1 % of the nonwhite mothers delivered of LBW infants who began prenatal care in the first trimester was not statistically different (t = 2.3360). For women ~ 25 years old the average percentages were 83.7% ± 4.2% for the white and 64.2% ± 4.7% for the nonwhite populations (t = 6.9177, P < 0.01). The mean annual rates of LBW infants born of singleton pregnancies to the white and nonwhite populations hetween the years 1977 and 1991 are tabulated by weight groups in Table V). Those infants weighing between 2001 and 2500 gm born to white women showed a small but statistically significant decrease in each 5-year increment. The incidence of LBW infants

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August 1994 Am J Obstet Gynecol

Table IV. Annual age-specific rates of resident singleton live births per 1000 women, percent out of wedlock for full weight, * and LBW per 1000 live births by age of mother and by race aggregated for 5-year increments 1977-1981

Age of mother <20 yr White Nonwhite 20-24 yr White Nonwhite 25-29 yr White Nonwhite 30-34 yr White Nonwhite >34 yr White Nonwhite

Live bzrths/1000 women (mean ± SD)

1982-1986

1987-1991

Percent out ofwedlock (mean)

LBW/lOOO lzve births (mean ± SD)

Lzve births/lOOO women (mean ± SD)

Percent out of wedlock (mean)

LBW/lOOO lzve births (mean ± SD)

Live births/lOOO women (mean ± SD)

33.0 ± 0.9 77.3 ± 3.0

25.6 [30.9%] 83.7 [86.6%]

75.0 ± 3.2 135.1 ± 6.2

30.8 ± 0.9t 63.9 ± l.4t

35.2 [41.2%] 89.7 [91.3%]

70.9 ± 1.8 126.1 ± 7.0

35.2 ± 3.4t 70.7 ± 4.4t

86.2 ± 1.1 130.6 ± 6.9

9.0 [15.1%] 49.3 [59.3%]

51.6 ± 1.6 107.9 ± 1.8

94.5 ± 2.0t 124.1 ± 5.0

13.5 [21.5%] 57.9 [69.0%]

50.9 ± 1.0 105.2 ± 4.0

93.6 ± 3.3 142.4 ± 6.8t

97.5 ± 1.6 104.0 ± 4.5

3.2 [6.5%] 27.2 [41.3%]

43.9 ± 1.7 86.5 ± 2.2

102.6 ± 2.5t 95.7 ± 5.0t

5.5 [11.0%] 34.2 [46.9%]

42.5 ± 1.0 92.3 ± 2.9t

108.1 ± 4.0t 107.5 ± 3.8t

58.9 ± 1.4 57.0 ± 2.3

2.4 [5.6%] 19.9 [35.1%]

43.8 ± 1.0 85.6 ± 3.5

66.6 ± 2.8t 56.6 ± 4.1

3.5 [6.9%] 25.5 [40.2%]

41.6 ± 1.6 93.7 ± 2.2t

78.0 ± 2.2t 62.5 ± 1.4t

9.7 ± 0.5 13.1 ± 0.5

3.8 [7.6'*] 20.4 [35.0%]

58.3 ± 3.8 103.6 ± 7.9

13.0 ± l.lt 12.6 ± 0.3

4.5 [10.1%] 22.4 [36.1%]

54.6 ± 5.7 103.9 ± 2.5

16.7 ± 1.2t 15.1 ± l.4t

55.3 ± 0.4 79.8 ± 3.5

7.8 [13.8%] 47.9 [61.8%]

51.1 ± 0.4 106.7 ± 2.4

57.4 ± 0.9t 69.0 ± 1.2t

10.3 [17.9%] 51.7 [65.1%]

48.5 ± 1.6t 104.6 ± 3.4

60.4 ± LOt 74.6 ± 2.4t

TOTAL

White Nonwhite

*Brackets indicate percent out-of-wedlock status of mothers delivered of LBW infants. tStatistically different (p < 0.05) from previous 5-year increment. :::Statistically different (p < 0.05) from LBW/1000 live births in 1977 to 1981.

weighing :s; 1500 gm did not vary statistically throughout the I5-year period. For the nonwhite population there was a statistically significant decrease in LBW rates for infants weighing 2001 to 2500 gm (t = 3.9510, P < 0.02) and 1501 to 2000 gm (t = 8.5381, P < 0.01) between 1977 to 1981 and 1987 to 1991. However, the annual rate of 3.5 ± 0.5 per 1000 live births calculated for the 1987 to 1991 increment for infants weighing < 500 gm is significantly greater than the rate recorded in 1977 to 1981 (t = 3.4513, P < 0.05). After 1977 to 1981 there was an 11.3% increase in the proportion of the LBW infants of the white population that were preterm, born before 36 completed weeks of gestation (t = 5.7613, P < 0.01). In the nonwhite population the increase was 14.5% (t = 8.4141, P < 0.001). The frequency of pre term singleton births, those delivered before 37 weeks of postmenstrual age, is listed in Table V by postmenstrual age groups and by race. Between 1977 to 1981 and 1987 to 1991 the frequency of pre term births in the white population increased during each 5-year increment. The greatest increase occurred in those infants born at 32 to 35 weeks' gestation. For the gestational period of :s; 28 weeks' postmenstrual age there was not a statistically significant change in the frequency of singleton births. The group of infants born during the thirty-sixth week of gestation and during the period of 28 to 31 weeks' postmenstrual age to the nonwhite mothers did not

vary statistically between 5-year increments. The proportion of preterm infants born at 32 to 35 weeks' gestation and those delivered before 28 completed weeks of gestation increased > 20%. In both populations there was an increase in infants weighing> 2500 gm delivered at ;;:: 32 weeks of postmenstrual age. The proportion of infants weighing > 2500 gm born during the thirty-sixth week of pregnancy increased from 66.9% ± 2.4% in 1977 to 1981 to 77.6% ± 1.0% in 1987 to 1991 for the white population (t = 9.2882, P < 0.001) and from 56.5% ± 2.1% to 65.1% ± 3.6% for the nonwhite population (t = 9.7506, P < 0.001). Of those infants delivered between 32 and 35 weeks the percentage of infants weighing > 2500 gm born to the white population increased from 31.6% ± 2.7% in 1977 to 1981 to 40.0% ± 1.1% in 1987 to 1991 (t = 6.1728, P < 0.01). The nonwhite population infants born 32 to 35 weeks' postmenstrual period increased 3.9% (27.2% ± 2.1%, 1977 to 1987; 31.1% ± 1.4%, 1987 to 1991, t = 4.4218, P < 0.01). Comment

Since 1966 the birth rate per 1000 females in the State of Virginia has decreased approximately 23o/c. However, the incidence of LBW infants has been reduced only 16%, indicating that preterm labor and delivery of LBW infants remain significant contributory factors in state neonatal and infant morbidity and mortality statistics.

Harbert

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Table V. Annual resident singleton LBW by weight and pre term births by weeks' gestation per 1000 live births by race aggregated for 5-year increments

1987-1991 Percent out o/wedlock (mean)

335

LB W/1 000 hve bIrths (mean ± SD)

48.3 [54.0%] 91.5 [93.0%]

70.6 ± 2.5 122.4 ± 3.4t

21.3 [30.6%] 63.7 [73.0%]

49.1 ± 2.0 99.4 ±

8.8 [16.3%] 39.7 [55.1%]

39.7 ± 1.5t,t 98.1 ± 4.8t

5.5 [12.2%] 30.0 [48.0%]

40.6 ± 1.0t 103.7 ± 8.0t

5.8 [12.1%] 28.0 [48.2%]

46.8 ± 3.3t 110.3 ± 10.4

14.4 [24.1%] 54.6 [68.0%]

45.8 ± 0.8U 103.1 ± 1.6t

3.n

1977-1981 (mean ± SD) LBW White 2001-2500 gm 1501-2000 gm 500-1500 gm <500 gm 'IOIAL

Percent preteI'm Nonwhite 2001-2500 gm 1501-2000 gm 500-1500 gm <500 gm 'I 0'1 AL

Percent preterm PreteI'm WhIte 36wk 32-35 wk 28-31 wk <28 wk TOrAL

Percent LBW Nonwhite 36wk 32-35 wk 28-31 wk <28 wk TOTAL

Percent LBW

1982-1986 (mean ± SD)

1987-1991 (mean ± SD)

33.9 9.2 7.1 0.8 51.1 54.6

± ± ± ± ± ±

0.7 0.4 0.4 0.1 0.4 1.9

31.9 8.8 6.9 0.9 48.5 58.5

± ± ± ± ± ±

0.8* 0.2 0.3 0.07 1.6* 1.5*

30.2 8.0 6.7 0.9 45.8 61.0

± ± ± ± ± ±

O.4*·t 0.3*·t 0.3 0.1 0.8*t 1.6t

66.6 21.1 17.3 2.6 106.7 55.2

± ± ± ± ± ±

2.2 0.5 0.8 0.3 2.4 1.4

64.5 19.1 18.0 2.9 104.6 58.6

± ± ± ± ± ±

2.4 1.1* 1.0 0.2 3.4 1.6*

62.4 18.4 18.7 3.5 103.1 63.2

± ± ± ± ± ±

0.9t 0.5t 1.3 0.5t 1.6t 1.6*'t

21.0 18.7 5.1 3.5 48.3 57.8

± ± ± ± ± ±

0.8 0.6 0.3 0.4 1.5 2.1

22.2 21.4 5.1 3.6 53.3 48.3

± ± ± ± ± ±

2.0 1.1* 0.2 0.2 2.0* 1.1*

24.5 23.4 5.3 3.8 57.1 48.4

± ± ± ± ± ±

O,6t 1.2t 0.1 0.3 1.8*·t 1.2t

34.1 34.5 11.7 10.3 85.5 66.5

± ± ± ± ± ±

1.0 1.4 0.6 0.4 2.1 1.3

33.9 37.6 12.0 11.1 95.5 64.9

± ± ± ± ± ±

1.6 1.0* 0.8 0.5* 2.0* 1.7

35.7 43.0 12.3 12.7 102.5 63.5

± ± ± ± ± ±

1.8 2.6*·t 0.6 l.4t 3.7*·t 0.9t

*Statistically different

The reviewed data revealed that the incidence of LBW infants born per 1000 live births to white residents of the State of Virginia decreased with each 5-year increment of study (Tables I and II). However, this decrease was noted only in those LBW infants weighing > 1501 gm. The rate per 1000 live births of VLBW infants weighing between 500 and 1500 gm remained unchanged throughout the 25-year interval, as did the incidence of infants weighing < 500 gm. LBW incidence for the nonwhite population, although essentially twice as high as that of the white population, decreased for most maternal age categories between 1967 to 1971 and 1987 to 1991. As for the white population, these decreases were engendered by those infants weighing > 1500 grams. For both races a milestone was reached in 1977 when for the first time the incidence of LBW infants for the white population dropped below 60 per 1000 live births and for the nonwhite population below 120 per 1000 live births. The reduction in the incidence of LBW noted in the 10 years 1967 to 1976 corresponded to an increase in the percentage of patients receiving prenatal care in the first trimester and the period when the number of maternity climes sponsored

by the State Health Department rose from 49 clinics seeing 1109 patients (1.3% of total live births) to 179 clinics seeing 6686 patients (9.5o/c of total live births). Approximately two thirds of the patients seen in these clinics were from the nonwhite population.' Virginia's perinatal centers have made significant strides in improving the most basic process of regionalization. Through increased maternal transport of pregnancies at risk a greater proportion of the right babies are being born in the right settings. This is evident on review of the difference in infant death rates between perinatal centers and regional and other hospitals (Table III). The benefits of regionalization and maternal transport are not as obvious when evaluation is based on the incidence of LBW infants or preteI'm birth. Chronologically the development of perinatal regions and the establishment of perinatal centers in Virginia corresponded with approval of ritodrine hydrochloride and the increased use of this and other tocolytic agents in efforts to prevent or suppress preterm labor or delivery. Increased use of tocolytic agents and management of labor of 43% of all patients delivered of LBW infants and 65% of those delivered of

336

Harbert

VLBW infants in perinatal centers has not resulted in a reduction of the incidence of LBW infants born in the State of Virginia. This lack of change lends credence to reports challenging the efficacy and widespread use of tocolytic agents" 4 and the statement that in the management of premature labor, "success in some instances may be on the basis of a clear instance of missed diagnosis."" Justification ofthe increased maternal morbidity resulting from prolonged inpatient treatment with tocolytic agents, especially in the presence of intact amniochorionic membranes, is also challenged. The decrease in the incidence of LBW resulted primarily from a reduction in births of infants that were intrauterine growth retarded or small for gestational age. Evaluation of preterm LBW infants (Table V) reveals that as the incidence of infants weighing between 1501 and 2500 gm decresaed for both white and nonwhite popUlations, the percentage of pre term LBW infants increased. The percentage of LBW infants weighing < 2500 gm delivered after 36 weeks of postmenstrual age in the white population decreased from 45.4% ± 1.9% in 1977 to 1981 to 39.0% ± 1.6% in 1987 to 1991 and for the nonwhite population from 44.8% ± 1.4% to 36.8% ± 1.6%. These decreases represent infants < 50th percf?ntage for weight at 37 weeks' postmenstrual age.? Further support of this concept is derived from review of pre term births (Table V). The median weight reported for the 36 week of postmenstrual age is 2650 gm 7 and the mean weight 2600 gm." The increase in infants weighing> 2500 gm in this time frame may reflect the decrease in intrauterine growthretarded and small-for-gestational-age infants. The increase in infants born in the 32 to 35 week postmenstrual age period weighing > 2500 gm may reflect errors in estimation of gestational duration. However, the 75th percentile weight at 34 weeks of postmenstrual age is reported as 2510 gm and the median weight at 35 weeks as 2430 gm. 7 An alternative possibility is an increase in the number of infants delivered in the upper range of the 32 to 35 week postmenstrual age period. This was the conclusion reached in a pilot program on preterm birth prevention conducted between 1983 and 1986 by one of the perinatal centers in Virginia. 9 Although relationships do not necessarily imply cause and effect, review of the rates of LBW associated with prenatal care received, marital status, age, race, and education have revealed that certain associations exist between these variables and the occurrence of LBW.1O The characteristics with the highest incidence of LBW were little or no prenatal care, not married to the father of the infant, maternal age < 20 years or > 34 years, nonwhite race, and less than a high school education. Others have reported that LBW appeared to be predicted by the number of prenatal visits made adjusted for gestational age in the trimester when prenatal care was initiated. II Data for the State of Virginia over a

August 1994 Am J Obstet Gynecol

25-year period support the association of some of these characteristics but do not establish clear cause-effect relationships. An increase in the percentage of patients beginning prenatal care in the first trimester was associated in time with a decrease in the incidence of LBW. However, both have plateaued since 1981 (Tables I, II, and IV). The proportion of women who began prenatal care in the first trimester and who experienced preterm labor or premature rupture of the membranes as a complication of their pregnancies was only slightly different from the percentage of patients beginning prenatal care in the first trimester for the total population (Table I). The percentage of ,women < 25 years old with singleton pregnancies beginning prenatal care in the first trimester did not differ from those giving birth to LBW infants and those delivered of infants weighing > 2500 gm. However, over age 25 years, there was a statistically significant 11.8% difference. The lack of change in the incidence of LBW infants weighing ::;1500 gm in both the white and the nonwhite populations, in spite of an increase in the percentage of patients receiving prenatal care in the first or second trimester, suggests that early prenatal care may not be a significant factor in preventing delivery of infants in this weight range. Further support of this possibility is found in the fact that > 80% of the white patients > 24 years old with singleton pregnancies and delivered of LBW infants had begun prenatal care in the first trimester. These findings also suggest that even with early prenatal care current medical knowledge cannot appreciably reduce the incidence of LBW and preterm births. The fact that the percentage of patients seeking prenatal care in the first and second trimesters has remained fairly constant since 1976 for all age groups, and for some actually decreased in 1987 to 1991, indicates that over the past 10 to 15 years efforts to further encourage early prenatal care have not resulted in measurable success. There has been a dramatic increase in out-of-wedlock births for both the white and nonwhite populations in all age categories. The age and population groups with the highest incidence of out-of-wedlock live births also experienced the highest incidence of LBW. However, a contributory association between marital status and LBW is suspect. The association of out-of-wedlock status with LBW was not consistent, as confirmed by the singleton pregnancy data (Table IV). In some instances, as exemplified by the nonwhite population in the 30- to 34-year-old category, a 36.8% increase in out-of-wedlock status was associated with a 21.1 % increase in the incidence of LBW. In others, exemplified by the nonwhite population 20 to 24 years old, a 23.1 % increase in out-of-wedlock status occurred during a period when there was a 7.8% decrease in the incidence of LBW. Still in other instances, white women > 34 weeks old, a

Volume 171, Kumber 2 Am J Obstet Gynecol

59.2% increase in out-of-wedlock status was associated with a 19.7% decrease in the incidence of LBW. These findings tend to dispel rather than support a strong cause-effect relationship between marital status and the occurrence of LBW or preterm births. Women < 20 years old consistently experienced the highest rate of LBW per 1000 live births (Table II). Women > 34 years old experienced the second highest rate in 1967 to 1971. However, the contributory significance of maternal age on the incidence of LBW for the state is changing. In 1967 to 1971 women <20 years old produced 19.2% of total live births but contributed 25.2% of LBW infants, a difference of 6%. This difference remained relatively constant through 1977 to 1981 but decreased to 4.9% in 1987 to 1991. Women 20 to 24 years old surpassed the women > 34 years old in contributing a higher percentage of LBW infants than their proportion of live births. The nonwhite population, in comparison to the white, has contributed a higher percentage of infants per 1000 live births to the LBW statistics, as evidenced in all maternal age groups (Tables II, IV, and V). The incidence of pre term birth is also approximately twice that of the white population, especially at < 36 weeks' postmenstrual age (Table V). This indicates that constitutional factors are not a significant contributor to the LBW difference between races, a conclusion supported by the report that deviations in weight between white and nonwhite fetuses before 36 weeks of gestation are not statistically significant. 7 The disproportionate contribution of the nonwhite race to the total number of live births, their higher percentage of LBW infants, and the lack of change in the incidence of LBW may tend to negate the decrease in LBW incidence of the white population in overall state statistics. However, this may be counterbalanced to some degree by the increase in the teenage birth rate of the white population between 1977 to 1981 and 1987 to 1991. Another racial difference is the greater contribution of multiple gestations by the white population to the LBW statistics, as evidenced by comparison of the rate of LBW for the total population (Table II) with data based on singleton pregnancies (Table IV). However, the increase in multiple gestations and their high incidence of LBW have not been a significant factor in the failure to lower LBW rates, as evidenced by data based on singleton gestations (Tables IV and V). The data reviewed are based on information filed by delivering physicians and other health care personnel. Consequently, it is only as accurate as the accoucheur makes it. Any errors or omissions made by some in supplying these data should be lessened in significance by the accuracy of others and the large numbers available when applied to a state population. The results, especially for the last 10 to 15 years, are discouraging. In spite of increases in the use of tocolytic agents,

Harbert 337

health department clinics, and programs targeted at problems considered to increase the risk of delivering a LBW or preterm infant, a dramatic impact has not occurred. What little success has been realized in reducing the incidence of LBW appears to apply primarily to those infants with other complications of pregnancy. In fact, maternal morbidity may have been increased by the inappropriate use of tocolytic agents in attempts to prevent or delay preterm delivery. The percentage of women seeking first-trimester prenatal care has generally remained stable, but in some instances has decreased. The percentage of both full-weight and LBW infants born out of wedlock has increased, as has the birth rate among white teenagers. These observations exemplifY the reality that increased social programs, availability of medical care, and new methods of medical management do not ensure patient participation or improved medical outcome; nor do they guarantee that the appropriate patient at risk will be selected to receive the correct care. No screening procedure currently available to identifY patients at high risk for preterm delivery has the sensitivity, specificity, and high predictive value to warrant unqualified acceptance. 1. 2 There is evidence that use of risk-factor scoring systems for preterm labor and delivery has directly led to an increase in obstetric intervention and tocolytic drug use. 12 Until more specific criteria are identified, initiation of any treatment should be highly selective. Efforts to reduce LBW and preterm births might best be directed to those women with a history of preterm delivery in a previous pregnancy, a known uterine abnormality. or a multiple gestation. The single group in which the greatest impact on LBW and preterm delivery statistics could be made are those women carrying more than one fetus. Plural births in 1987 to 1991 composed only 2.3% of total live births in Virginia but contributed 17.0% of the LBW infants. Even when a patient is identified as being at risk for LBW or preterm birth, the most effective form of management remains an enigma. Contractions of the uterus of varying degree occur as a normal physiologic event throughout pregnancy. Efforts to distinguish these contractions from early symptoms of impending preterm labor either by patient perception or electronic monitoring of uterine activity have limited accuracy. 2 The benefits of antibiotic therapy, 13. 14 home uterine monitoring, 1 and the benefits versus risks of prolonged use of tocolytic agents" 4 are not resolved. The geographic proximity and increased maternal transport and patient volume of the perinatal centers in Virginia offer an opportunity for collaborative endeavors with specific prospective protocols to address of these and other management controversies. The data on deaths of infants < 1 week old (Table III) document that the best chance of survival for

338

Harbert

infants weighing ~ 1500 gm occurs if they are born in a perinatal center. Every effort should be made to assure that the right babies are born in the right settings. The widespread availability of ultrasonography to confirm the duration of pregnancy and estimate fetal weight can facilitate identification of these fetuses at risk of weighing < 1501 gm or at < 32 weeks' postmenstrual age to ensure maternal referral to a perinatal center. REFERENCES 1. Creasy RK. Preterm birth prevention: where are we? A'v!]

OBSTE1 GYNECOL 1993;168:1223-30. 2. McLean M, Walters WAW, Smith R. Prediction and early diagnosis of preterm labor: a critical review. Obstet Gynecol Surv 1993;48:209-25. 3. The Canadian Preterm Labor Investigators' Group. The treatment of preterm labor with the beta-adrenergic agonist ritodrine. N Engl] Med 1992;327:308-12. 4. Higby K, Xenakis EM], Pauerstein CJ. Do tocolytic agents stop preterm labor? A critical and comprehemive review of efficacy and safety. AM] OBSfE1 GYNECOL 1993;168: 1247-59. 5. Trends in pregnancies and infant deaths through 1987. In: Virginia vital statistics. Richmond, Virginia: Virginia Department of Health, 1989. 6. Harbert GM, Spisso KR. The management of preterm labor: use ot magnesIUm sulfate. In: Zuspan FP, Christian CD, eds. Volume 3: controversy in obstetrics and gynecology, Philadelphia: WB Saunders, 1983:73-9. 7. Brenner WE, Eldelman DA. Hendncks CH. A standard of fetal growth for the United States of America. AM] OBSTET GYNECOL 1976;126:555-64. 8. Goldenberg RL, Nelson KG. Da~is RO, Koski J. Delay in delIvery: influence of gestational age and the duration of delay on perinatal outcome. Obstet Gynecol 1984,64: 480-4. 9. Statewide perinatal services plan. Richmond, Vlrgillla: Virginia Department of Health, 1988: 14-6. 10. Fedrick], Anderson ABM. Factors as~oClated WIth spontaneous preterm birth. Br J Obstet Gynaecol 1976;83:34250. II. Gortmaker SL. The effects of prenatal care upon the health of the newborn. Am] Public Health 1979;69:65360. 12. Keirse MJNC. Betamimetic drugs in the prophylaxis of preterm labor. Extent and rationale of their use. Br ] Obstet Gynaecol 1984;91:431-7. 13. KIrschbaum T. Antibiotic, in the treatment of pre term labor. AM] OBSTFT GYNECOL 1993;168:1239-46. 14. Romero R, Sabai B, Caritis S, et al. Antibiotic treatment of preterm labor with intact membranes: a multicenter, randomized, double-blinded. placebo-controlled trial. AM J OBsn:r GYNF,CQL 1993;169:764-74.

Discussion DR. JANICE W. JOHNSTON, Atlanta, Georgia (Official Guest). This study reviews the birth statistics of Virginia over a 25-year period. Specifically, it summarizes the data collected on the incidence of LBW in 5-year increments from 1967 through 1991. During this time span various efforts by the State of Virginia to improve obstetric outcome and decrease the incidence of preterm birth - increased number and use of State Health Department maternity clinics, identification and modification of pre term risk factors, regionalization, and expanded Medicaid eligibility-are cited. The increased use of tocolytic agents was also noted during this period.

Aug"" 1994 Am J Obstet Gvnecol

Although the incidence of LBW declined between 1967 and 1981, there has been little change in the last 10 to 15 years. More specifically, Harbert notes the disappointing finding of no change in the incidence per 1000 live births of infants weighing 500 to 1500 gm during the 25 years. He suggests that the data challenge the overall effectiveness of current prematurity prevention programs. He is not alone in questioning the effectiveness of current efforts to reduce pre term birilis. The Collaborative Group on Preterm Birth Prevention' and other authors" have drawn similar conclusions, because reliable and reproducible benefits have not been found. Furthermore, the effectiveness of tocolytic agents, home uterine monitoring, and antibiotics in the management of preterm labor has been challenged. 3 - b Although the current programs and efforts appear to be ineffective, caution must be urged against abandoning such programs. Whenever we discuss improved obstetric outcomes, we are compelled to direct our attention not only to the problem of preterm birth but also infant mortality.7, " Infant mortality is used as a standard index of health. Preterm birth, infant mortality, and risk factors are linked together. Although LBW infants accounted for 6.9% of infants born in the United States in 1987 (the most recent data available), 61% of all infant deaths occurred in this group. In 1991 the infant mortality rate for the United States was 8.9 infant deaths per 1000 live births - the lowest rate ever recorded and a decrease from 9.2 for 1990. The four leading causes of infant mortality account for approximately 50% of all deaths among infants. These causes include congenital anomalies, sudden infant death syndrome, preterm birth or LBW, and respiratory distress syndrome. The most important risk for infant mortality is LBW." Survival increa5es exponentially as birth weight increases to an optimum level. Other factors that have increased risk for infant mortality include black race, extremes of maternal age, lower educational status, and lack of prenatal care. Black infants carry double the risk of preterm birth and death compared with white infants.? The most recent available national data (1991) from the Centers for Disease Control and Prevention rank prematurityLBW as the leading cause of infant mortality in blacks. Furthermore, the gap in infant mortality between black and white infants has increased. The data presented by Harbert on infant mortality within the first week of life demonstrates a progressive decline during the last 15 years-from 8.73 to 5.47 per 1000 live births. These findings are consistent in each LBW group. Although preterm-LBW infant mortality has declined steadily over the years, the problem of infant morbidity is significant. Short- and long-term morbidity in the preterm-LBW, and in particular the VLBW, infant is tremendous. Consider these sobering facts related to infant morbidity in Georgia in 1991: (1) 9475 (8.6%) infants were born weighing < 2500 gm; (2) 8641 (91.2%) of the 9475 infants survived; (3) 6334 infants required neonatal intensive care at a hospital cost of

Volume 171. Number 2 Am] Obstet Gynecol

$18,648 per baby; (4) 507 of these 6334 infants will experience serious disabilities that prevent normal functioning; and (5) 1198 infants weighed < 1000 gm. of which 40% will be mentally retarded. 10% will be blind. and 8% will be deaf. Unfortunately, there are not many studies that address the differences seen in public clinic versus private patients. Meis et a1. 9 and Gazaway and Mullins lo found significant differences in the reasons for LBW delivery for private and public patients. Idiopathic premature labor accounts for 47% of private patient LBW deliveries but only 25% of public patient LBW deliveries. LBW premature rupture of membranes is more common in public patients (34%) than in private patients (23%). The success of a prematurity prevention program may depend on the characteristics of the program and the patient population that it targets. Preterm birth is a social problem as well as a medical problem. Social factors that are risk factors for preterm delivery such as age at conception, educational status, socioeconomic status, and marital status should be addressed. Preterm birth prevention programs should include birth (conception) prevention programs. Girls < 18 years old should not be having babies. Efforts should be directed at having girls complete 12 years of school before completing 40 weeks of gestation. Investigators should be encouraged to design innovative prematurity prevention programs. Research should be directed at understanding the pathophysiologic mechanisms of labor. Only then can we successfully predict, prevent, and treat premature labor. Preventing preterm delivery is our primary goal, and decreasing infant mortality is our ultimate goal. Indeed, pre term birth is a complex problem that most likely will have a complex solution. The article raises a number of questions. Were any programs in Virginia designed specifically to narrow the gap in the incidence of preterm delivery between the white and nonwhite population? Although cause and effect should not be mistaken, did the author preform a regression analysis of factors such as age, years of education, number of prenatal visits, etc.? In light of this and other recent data that challenge current prematurity prevention programs, does the author use and recommend tocolytic agents? What would the author target for change in a prematurity prevention program today? What effect will managed health care and universal coverage have on the incidence of LBW and preterm birth? REFERENCES 1. Collaborative Group on Preterm Birth Prevention. Multicenter randomized. controlled tnal of a preterm birth preventIOn program. A\I] OBsnr GYN~COL 1993; 169:35266. 2. Main DM, Richardson DK. Hadley CB. Gabbe SG. Controlled trial of preterm labor detection program: efficacy and costs. Obstet Gynecol 1989;74:873-7. 3. The Canadian Preterm Labor Investigators' Group. The treatment of preterm labor with beta-adrenerglCs agonist ritodrine. N Engl] Med 1992;327:308-12. 4. Higby K. Xenakis EM. Pauerstein CJ. Do tocolytic agents stop preterm labor? A critical and comprehemive leview of effICacy and satety. A~! J OB51£T GYNECOL 1993;168: 1247-59.

Harbert

339

5. Romero R, Sibai B, Caritis S. et al. Antibiotic treatment of preterm labor with IIltact membranes: a multicenter, randomized, double-blinded, placebo-controlled trial. AM .J OB,TET GY:>IECOL 1993:169:764-74. 6. Grimes DA. Schultz KF. Randomized controlled trials of home uterine activity monitoring: a review and critique. Obstet Gynecol 1992;79: 137-42. 7. Centers for Disease Control and Prevention. Infant mortality-United States, 1991. MMWR 1993A2:926-30. 8. Centers for Disease Control and Prevention. National infant mortality surveillance (NIMS) 1980. MMWR 1989; 38:1-46. 9. Meis P], EmestJM, Moore ML. Causes oflow birth weight births in public and pnvate patients. AM] OBsTn GY:>l~('OL 1987; 156: 1165-8. 10. Gazaway P, Mullins CL. Prevention of preterm labor and premature rupture of the membranes. Clin Obstet Gynewl 1986;29:835-49.

DR. CARLYLE CRENSHAW, Baltimore, Maryland (Guest Speaker). I certainly agree that there is no evidence that prenatal care decreases the incidence of prematurity. We can use the state of Maryland as a good example. We have one of the best records of early prenatal care and total prenatal care of any state in the country. By last report, we were seventh or eighth. However, we have one of the worst rates of prematurity and infant death in the country, although this state is somewhere around seventh in average income. The other thing that I would certainly agree with is that, to my knowledge, there is no tocolytic agent that will prevent premature delivery. We don't talk about preventing premature delivery anymore. We talk about delay of delivery, and among the data that I presented yesterday one fact that is very important is that in patients at 25 to 29 weeks' gestational age our median delay of delivery was 7 days. During this time we can certainly improve certain conditions in the mother, we can help improve the pulmonary status of the fetus in utero, and we can give our neonatal colleagues a better chance to improve the outcome of the babies that we deliver. DR. ROBERT M. STAFFORD, Charleston, South Carolina. I didn't hear anything about the incidence of drugscreen testing in these patients. I think there is a tocolytic method, if not agent, that we can use that might decrease pre term labor by up to 309C, and that is routine drug screening in these patients in the prenatal period. If those patients taking drugs that are associated with preterm labor can be identified early in pregnancy, the incidence of preterm labor may be decreased. DR. HARBERT (Closing). I'll answer Johnston's last question first. What effect will managed health care have on the incidence of LBW and preterm delivery? I haven't got the slightest idea. Several studies have been done by various perinatal centers on trying to reduce LBW. None of them were specifically designed for the white versus the nonwhite population. It just so happened that one of them was in Charlottesville, which as mentioned is 80% white; one of the studies was in Richmond, which has a considerahly greater proportion of hlack population; and one in Norfolk, which is about 50-50.

Harris and Olive

What effect has age, education, and the number of prenatal visits had on the incidence of LBW? These data were available. Suffice it to say that only those patients with greater than a twelfth grade education regardless of age, and obviously that omits some of the teenagers, had a 95% incidence of first- or secondtrimester prenatal care. The number of prenatal visits has been questioned as an indication of the adequacy of care, with 10 being the desired number according to some reports; however, with preterm labor, it may not be possible to reach this particular category. What is our use of tocolytic agents? I first started this program when I heard Pauerstein say that magnesium sulfate does not work and should not be used. I've used magnesium sulfate for 25 years. I was going to show that he was wrong. I didn't do it.

August 1994 Am J Onstet Gynecol

I still use tocolytic agents. I think I'm going to be using them less, because I'm going to be a little more selective. I think we may have increased the morbidity of the mother and the cost of hospitalization by treating people who do not need to be treated. I think we should perform collaborative efforts within our state or within perinatal centers. If the six perinatal centers in Virginia can get together with a common protocol in delivering 90,000 live births a year, it wouldn't take us 100 long to answer some of these questions. I do not have data on drug screening. However, these statistics do include the patients reported on by Dinsmoor regarding cocaine screening in the state of Virginia.

Changing hysterectomy patterns after introduction of laparoscopically assisted vaginal hysterectomy Mary B. Harris, MD: and David L. Olive, MDb Lumberton, North Carolina, and New Haven, Connecticut OBJECTIVE: The objective of this study was to determine whether introduction of laparoscopically assisted vaginal hysterectomy decreases the percentage of women requiring laparotomy for hysterectomy. STUDY DESIGN: A retrospective review of women undergoing hysterectomies from 1990 through 1992 was performed. Type of hysterectomy and total hospital charges were determined. Indication for surgery and complicatons in the laparoscopicafly assisted vaginal hysterectomy group were also examined. RESULTS: During the study interval 670 hysterectomies were performed. In 1990 and 1991 abdominal hysterectomies comprised 51.5% and 45.5% of all hysterectomies, respectively. After introduction of laparoscopically assisted vaginal hysterectomy in 1992 the percentage of abdominal hysterectomies declined to 35.6%, whereas the percentage of unassisted vaginal hysterectomies remained stable. The complication rate for patients with laparoscopically assisted vaginal hysterectomy was 16%. Average cost was $11,931 compared with $7031 for abdominal hysterectomy and $5343 for vaginal hysterectomy. CONCLUSION: Laparoscopically assisted vaginal hysterectomy can decrease the number of patients requiring a laparotomy for hysterectomy but at a much greater cost. (AM J OSSTET GVNECOL 1994;171 :340-4.)

Key words: Laparoscopically assisted vaginal hysterectomy, assisted vaginal hysterectomy, trends, cost

From the Drpartmmt of ObstetriCs and Gynecology. Southeastern RegIOnal MedICal Center,a and the Section of Reproductive Endocrinology and Infertlhty. Department oj Obstetrus and Gynecology, Yale Umvenl!y School of Mnizcme." Presrnted as Officwl Guest at the FiftY-Sixth Annual Meetmg of The South AtlantiC AssoaatlOn of Obstetncwns and Gynecologists. Orlando, Flonda, January 15-18, 1994. Reprmt requeltl. Milry B. Hams, MD, 4300 Favetteville Road, Lumberton, NC 28358 Cop'yrlght © 1994 b.y Mosb'y-l'ear Book. Inc. 0002-9378/94 $3.00 + 0 6/6/56548

Since it was first reported in 1989 1 the number of hysterectomies performed with Iaparoscopic assistance has grown steadily. Perceived benefits include decreased hospital stay, less pain, rapid recovery, and fewer complications. These advantages, however, are predicated on the assumption that laparo5copically assisted vaginal hysterectomy is replacing hysterectomy by laparotomy rather than substituting for unassisted vaginal hysterectomy. Although there have been a num-