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Pregnancy outcome in women with morbid obesity
International Journal of Gynecology & Obstetrics 73 Ž2001. 101᎐107
Article
Pregnancy outcome in women with morbid obesity A.S. KumariU Department of Obstetrics and Gynecology, Al-Mafraq Hospital, Abu Dhabi, United Arab Emirates Received 30 June 2000; received in revised form 22 November 2000; accepted 29 November 2000
Abstract Objecti¨ e: To study the effects of morbid obesity defined as a first trimester maternal body mass index of ) 40 on the perinatal outcome. Methods: One hundred and eighty-eight singleton pregnancies of women with first trimester BMI ) 40 who delivered at Al-Mafraq Hospital, Abu Dhabi during 1996᎐1998 were studied. A control group of normal body mass index matched for age and parity were selected and the perinatal variables were compared between groups. Morbidly obese women with diabetes and hypertension antedating the index pregnancy were later excluded and the data were re-analyzed. Results: Morbidly obese women were noted to have significantly adverse perinatal outcomes including hypertensive disorders of pregnancy Ž28.8 vs. 2.9%, P- 0.0001., gestational diabetes Ž24.5 vs. 2.2%, P - 0.0001., cesarian section Ž15.2 vs. 9.3%, P- 0.05. and macrosomia Ž32.6 vs. 9.3%, P- 0.001. compared to non-obese women. However, we noted a significantly lower rate of prematurity in the obese group Ž0.5 vs. 5.3%, P- 0.001.. Even when morbidly obese women with Ža. diabetes and hypertension antedating the index pregnancy and Žb. those who developed gestational diabetes andror pregnancy-induced hypertension during the index pregnancy were excluded from the analysis, significant differences in the perinatal outcomes still persisted. Conclusion: Morbid obesity appears to be an independent risk factor for adverse perinatal outcome. 䊚 2001 International Federation of Gynecology and Obstetrics. All rights reserved. Keywords: Morbid obesity; Pregnancy; Perinatal outcome; Gestational diabetes; Macrosomia
1. Introduction During the past 3 decades United Arab Emirates ŽUAE., like all other Gulf States has experienced drastic changes in socio-economic conditions and food habits. These changes have an U
Al-Mafraq Hospital, Department of Obstetrics and Gynecology, P.O. Box 2951, Abu Dhabi, United Arab Emirates. Fax: q971-258-21549. E-mail address: [email protected] ŽA.S. Kumari..
immense influence on the lifestyles and disease patterns in this region. Obesity, a non-communicable disease has assumed an epidemic proportion. While obesity has been established as a risk factor for diabetes mellitus, hypertension, coronary artery disease and stroke, much less is known about the risks of maternal obesity on perinatal outcomes. The 1992 UAE National Nutrition survey w1x based on body mass index revealed that 33% of married women were overweight and 38% were obese. Since age and parity pre-dispose to
0020-7292r01r$20.00 䊚 2001 International Federation of Gynecology and Obstetrics. All rights reserved. PII: S 0 0 2 0 - 7 2 9 2 Ž 0 0 . 0 0 3 9 1 - X
102
A.S. Kumari r International Journal of Gynecology & Obstetrics 73 (2001) 101᎐107
obesity, it is not a surprise that the age-adjusted obesity rate in females exceeds that in males. This trend is particularly prevalent in the Gulf States where a prolonged reproductive span starting in early teens and extending into late forties leads to high parity. All these factors have led to a large numbers of grossly obese women requiring obstetric services. Several publications suggest the adverse effects of obesity on the perinatal outcome. The literature has reported increased incidence of gestational diabetes mellitus ŽGDM., pregnancy-induced hypertension ŽPIH., macrosomia, intrauterine growth retardation, operative deliveries and perinatal mortality w2᎐9x. The complications of anesthesia and surgery in obese individuals are well known and include: difficulties in intubation and ventilation; prolonged operative time; increased blood loss; post-operative infection; and deep venous thrombosis. However, other studies have concluded that obesity by itself is not an independent risk factor for adverse perinatal outcome w10x. This controversy is related to the variance in the definition of obesity, varied population sample size and inadequate control of confounding factors. Obesity is commonly defined in terms of body mass index ŽBMI. ŽWrH 2 . or as a percentage of ideal body weight determined from actuarial tables. It has been defined as a body weight of above 80᎐135 kg, a weight 50᎐300% more than ideal pre-pregnancy weight and a BMI of 30 and above. These varying definitions among different populations make comparison of results difficult. BMI has been used in large population surveys for prevalence of obesity. For the purpose of our study we used Garrow’s grading of obesity based on the Quetlet index or BMI which is weight in kgrheight in m2 w11x. Grade 0 Žnormal. 1 Žoverweight. 2 Žobese. 3 Žmorbidly obese.
BMI wkgrm2 x; 20᎐24.9; 25᎐29.9; 30᎐40; ) 40.
The objective of this study was to determine if pregnant women with grade 3 obesity are at higher
risk of adverse perinatal outcomes than non-obese women.
2. Materials and methods A retrospective study was conducted at the maternity unit of Al-Mafraq hospital, Abu-Dhabi, United Arab Emirates comparing morbidly obese and non-obese women who delivered a singleton between 1996 and 1998. All women who attended the antenatal clinic with a weight of 90 kg and above during the first 12 weeks of pregnancy were selected and their BMI calculated. Women with BMI equal to or more than 40 were included in the study group. When women delivered more than once during the study period only the first pregnancy was used for analysis. Women with first trimester weight - 70 kg and a BMI between 22 and 28, matched for age and parity and who delivered within the fortnight preceding or following the index pregnancy served as controls Žnon-obese group.. The senior charge nurse of the labor and delivery unit collected the data of the control group and was totally blinded to the outcomes of the morbidly obese group. The complete data regarding maternal variables, medical disorders, peripartum and neonatal complications were obtained from delivery room records and prospectively entered into computerized forms. Any missing information was obtained by review of patient’s personal charts. The incidence of selected maternal, peripartum and neonatal outcomes were analyzed in the two groups. The maternal variables studied included age, parity and BMI. Pre-existing medical disorders studied included chronic hypertension and diabetes mellitus. The antepartum variables analyzed were gestational diabetes, pregnancyinduced hypertension, placenta previa, abruption and intrauterine growth retardation. Intrapartum variables studied were shoulder dystocia, cesarian section and preterm labor. The neonatal variables examined were low birth weight Ž- 2500 g., macrosomia Žbirth wt.) 4000 g., low Apgar scores Ž- 7 at 1 min., neonatal intensive care unit ŽNICU. admissions and stillbirths. In order to exclude the influence of medical
A.S. Kumari r International Journal of Gynecology & Obstetrics 73 (2001) 101᎐107
disorders antedating the index pregnancy on the obstetric outcome, morbidly obese women with a diagnosis of chronic hypertension andror diabetes antedating pregnancy were excluded and the outcome variables were re-analyzed. To assess the independent influence of morbid obesity on perinatal outcome, a sub-analysis of morbidly obese women without gestational diabetes and pregnancy-induced hypertension was made. The statistical analysis was performed by using 2 test, odds ratios and 95% confidence intervals were calculated and the significance was defined as P- 0.05.
3. Results One hundred and eighty-eight morbidly obese women and 300 non-obese women matched for age and parity were compared. The maternal demographic variables of each group are presented in Table 1. The antenatal variables are given in Table 2. A significantly higher rate of gestational diabetes Ž P- 0.001. and pregnancyinduced hypertension Ž P- 0.001. was noted in the morbidly obese women as compared to the non-obese group. No significant differences were noted among the groups as regards placental complications and IUGR. Selected intrapartum variables are shown in Table 3. A significantly higher cesarian section rate was seen in the morbidly obese group as compared to the non-obese group Ž P- 0.001., mainly because the obese women had a higher elective cesarian section rate Ž9.6 vs. 3%.. Surprisingly, a lower rate of prematurity was noted in the morbidly obese group Ž P- 0.001. inspite of higher rate of pregnancy-induced hypertension. Table 4 illustrates the neonatal variables. Neonates born to morbidly obese women exhibited a high rate of macrosomia Ž P0.001. and a higher rate of admission to NICU as compared to the non-obese group. The rate of small for gestational age ŽSGA. neonates, although less in the obese group as compared with non-obese group Ž1.6 vs. 5.3%. did not attain statistical significance Ž P- 0.1.. There was a higher rate of stillbirths among morbidly obese women as compared with the non-obese women
103
Table 1 Maternal variables Parameters
Obese Ž n s 188.
Non-obese Ž n s 300.
Age Žyears.
31.66" 5.79 Ž16᎐45. 5.49" 2.46 Ž1᎐13. 44.05" 3.99 Ž40᎐56.
31.78" 5.58 Ž16᎐46. 5.38" 2.52 Ž1᎐13. 25.13" 3.26 Ž22᎐28.
Parity BMI Žkgrm2 .
Ž3.2 vs. 0.7%. but did not reach statistical significance Ž P- 0.06.. Twenty-nine women among the morbidly obese group had diabetes mellitus andror chronic hypertension antedating pregnancy. These were excluded from the study group and the data were re-analyzed. The results are illustrated in Table 5. The increased rates of pregnancy-induced hypertension, gestational diabetes, cesarian section and macrosomia persisted even after controlling for medical complications. Among the morbidly obese group 97 women did not develop gestational diabetes andror pregnancy-induced hypertension. The perinatal outcome in this group is illustrated in Table 6. Significantly higher rates of cesarian section, macrosomia and NICU admissions were noted in these women.
4. Discussion As suggested by Garrow w11x a BMI of 40 and above was used to define morbid obesity. The BMI was calculated from the weight taken during the first antenatal visit before 12 weeks of pregnancy. This BMI reflects pre-pregnancy BMI, since the majority of women during the first trimester lose rather than gain weight. The mean BMI of the control group was 25.13 which was marginally above the normal weight range thus, the non-obese group is composed of women with normal BMI and overweight women. Wolfe et al. w12x reported that both BMI and simple gravid weight comparably predicted the outcome variables in obese pregnant women.
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Table 2 Antenatal variables Variables
Diabetes Total Antedating pregnancy Gestational diabetes Chronic hypertension Pregnancy-induced HTN Placenta previa Abruptio placenta IUGR
Obese Ž n s 188. No. Ž%.
Non-obese Ž n s 300. No. Ž%.
P value
Odds ratio
95% confidence interval
68 Ž36.2. 24 Ž12.8. 44 Ž23.4. 8 Ž4.3. 54 Ž28.7. 1 Ž0.5. 1 Ž0.5. 2 Ž1.0.
8 Ž2.5. 4 Ž1.3. 4 Ž1.3. 1 Ž0.3. 9 Ž3.0. 2 Ž0.7. 1 Ž0.3. 3 Ž1.0.
- 0.0001 - 0.0001 - 0.0001 - 0.1 NS - 0.001 NS NS NS
20.7 10.8 22.6 13.3 3.0 0.8 1.6 1.1
9.6᎐44.3 3.7᎐31.7 8.0᎐64.1 1.6᎐107 6.2᎐27 0.1᎐8.8 0.1᎐25 0.2᎐6.4
Since our population is multiracial and multiethnic with different anthropometric standards we chose BMI rather than simple weight measurements to define morbid obesity. As noted in the literature w4,5,9,10x there was significantly higher frequency of diabetes mellitus antedating pregnancy in morbidly obese women when compared to the non-obese group Ž12.8 vs. 1.3%.. Compared to the literature, the rate of chronic hypertension in the study group was low Ž4.3%. probably reflecting racial differences. There was a significantly higher rate of gestational diabetes in the obese group Ž25.8 vs. 1.3% in the non-obese group.. This rate is higher than that reported by other studies w2,3,10x. This discrepancy could be due to the overall higher prevalence of diabetes mellitus in the Gulf countries w1x. Concordant to the literature w2,3,10,13x, there was a significantly higher occurrence of
pre-eclampsia in the morbidly obese group Ž28.7 vs. 3%.. This high rate persisted even when women with diabetes and hypertension antedating pregnancy were excluded from analysis Ž25.8 vs. 3%.. The cesarian section rate in the morbidly obese group was significantly higher Ž19.1 vs. 9.3%. and was contributed mainly by the higher elective cesarian section rate of 9.6% compared to only 3% in the non-obese group. Fifty percent of the cesarian sections of the obese group and 32% in the non-obese group were elective due to the presence of a combination of factors like inadequately controlled diabetes, hypertension, macrosomia, previous shoulder dystocia and failure of induction. The emergency sections were done mostly for arrest disorders. These results are consistent with many previous reports w2᎐5,8,9x. These differences persisted even when pre-existing diabetic and hypertensive women were excluded from
Table 3 Intrapartum variables Parameters
Cesarian section Elective Emergency Total Preterm delivery Shoulder dystocia
Obese Ž n s 188. No. Ž%.
Non-obese Ž n s 300. No. Ž%.
P value
Odds ratio
95% confidence interval
18 Ž9.6. 18 Ž9.6. 36 Ž19.1. 1 Ž0.5. 4 Ž2.1.
9 Ž3.0. 19 Ž6.3. 28 Ž9.3. 16 Ž5.3. 2 Ž0.7.
- 0.01 - 0.2 - 0.001 - 0.001 - 0.2
3.4 1.6 2.3 0.1 3.2
1.5᎐7.8 0.8᎐3.1 1.4᎐3.9 0.01᎐0.7 0.6᎐17.7
A.S. Kumari r International Journal of Gynecology & Obstetrics 73 (2001) 101᎐107
105
Table 4 Neonatal variables Obese Ž n s 188. No. Ž%.
Non-obese Ž n s 300. No. Ž%.
P-value
Odds ratio
95% confidence interval
Birth weight ) 4000 g - 2500 g Low apgar Ž- 7 at 1 min.
58 Ž30.9. 3 Ž1.6. 4 Ž2.1.
31 Ž10.3. 16 Ž5.3. 6 Ž2.0.
- 0.001 0.10 NS - 0.31 NS
3.9 0.3 1.1
2.4᎐6.3 0.1᎐1.0 0.3᎐3.8
NICU admission Still birth
30 Ž16. 6 Ž3.2.
12 Ž4.0. 2 Ž0.7.
- 0.001 - 0.06
4.6 4.9
2.3᎐9.1 1.0᎐24.6
Outcome
analysis. Garbaciak et al. w9x reported similar findings suggesting that obesity per se leads to an increased risk of cesarian section with all its subsequent complications. This contrasts with the study of Parlow et al. w10x who suggested that obesity per se was not associated with higher cesarian section rates. Despite a high rate of pre-eclampsia and gestational diabetes there was a significantly lower rate of preterm labor Ž0.5 vs. 5.3%. among the morbidly obese group. Wolfe w14x also stated that preterm delivery among obese women is half of that in normal women. These results are in contrast to those of Bianco et al. w2x and Cnattingius et al. w7x. Many studies w2,3,8,10x have demonstrated that morbidly obese women are more likely to deliver large for gestational age neonates. The rate of macrosomia among morbidly obese women was higher Ž30.9 vs. 10.3%. than the reported rate in the literature. This could be explained by the high frequency of gestational diabetes among our
women, since it persisted even after controlling for pre-existing diabetes and hypertension. The rate of small for gestational age ŽSGA. neonates was less in the morbidly obese group than in the control group Ž1.6 vs. 5.3%., although this difference did not reach statistical significance. This is consistent with many previous studies w2,6᎐8x and probably suggests the protective role of maternal obesity against birth of SGA infants. The higher incidence of SGA noted in few studies w10x could be related to chronic hypertension and diabetic vasculopathy complicating these pregnancies. Obesity in pregnant women is associated with an increased risk of perinatal mortality w5᎐7,15x. We also noted an increased incidence of stillbirths in the morbidly obese group Ž3.2 vs. 0.7%.. However, majority of these stillbirths were in diabetic women and when these were excluded from analysis there were no significant differences between groups and is in contrast to the study of Cnattingius w7x. Admissions to NICU
Table 5 Perinatal outcome excluding morbidly obese women with diabetes and chronic hypertension antedating pregnancy Outcome
Obese Ž n s 159. No. Ž%.
Non-obese Ž n s 300. No. Ž%.
P-value
Odds ratio
95% confidence interval
Gestational diabetes Pregnancy-induced HTN Cesarian section Macrosomia Still birth
41 Ž5.8. 41 Ž25.8. 26 Ž16.3. 44 Ž27.7. 1 Ž0.6.
4 Ž1.3. 9 Ž3.0. 28 Ž9.3. 31 Ž10.3. 2 Ž0.7.
- 0.001 - 0.001 - 0.001 - 0.001 NS
25.7 11.2 1.9 3.3 0.9
9.0᎐73.4 5.3᎐23.8 1.1᎐3.4 2.0᎐5.5 0.1᎐10.5
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A.S. Kumari r International Journal of Gynecology & Obstetrics 73 (2001) 101᎐107
Table 6 Perinatal outcome excluding gestational diabetes and pregnancy-induced hypertension in morbidly obese and non-obese groups Outcome
Cesarian section Emergency Elective Total Macrosomia Low apgar Ž- 7 at 1 min. NICU admission Still birth
Obese Ž n s 97. No. Ž%.
Non-obese Ž n s 285. No. Ž%.
7 Ž7.2. 8 Ž8.2. 15 Ž15.4. 26 Ž26.8. 2 Ž2.1. 15 Ž15.5. 1 Ž1.0.
7 Ž2.5. 13 Ž4.5. 20 Ž7.0. 25 Ž8.8. 4 Ž1.4. 7 Ž2.5. 1 Ž0.4.
were more frequent in the morbidly obese group Ž16 vs. 4%. and were contributed mainly by macrosomic infants. Since GDM and PIH may be the causal mechanisms for adverse perinatal outcomes in morbidly obese women w7x, many of the studies have not controlled for these variables in their analysis. In our study, in the sub-group of morbidly obese women after controlling for GDM and PIH, we still noted higher rates of cesarian section Ž15.4 vs. 7%., macrosomia Ž26.8 vs. 8.8%. and NICU admissions Ž15.5 vs. 2.5%.. Bianco et al. w2x noted high rate of macrosomia in their study after controlling only for gestational diabetes. This probably suggests that obesity can cause sub-optimal perinatal outcome through mechanisms other than GDM and PIH. From the results it appears that morbid obesity is an independent risk factor for adverse perinatal outcomes. Maternal obesity may be one of the most important preventable risk factors for perinatal mortality. Prenatal counseling of obese women regarding weight reduction and healthy food habits seems vital. The excessive weight gain during pregnancy above the recommended standards in the Arabian Gulf women w1x and the high parity contributes to progressive obesity and its consequent risks. In the morbidly obese pregnant women, the effects of dietary interventions in modifying adverse perinatal outcomes are not yet proven. Every effort should be made to prevent increasing body weight and encourage women to return to pre-pregnancy weight and reach a normal body mass index before the next pregnancy.
P-value
Odds ratio
95% confidence interval
- 0.04 - 0.001 0.6 - 0.001 0.62
2.4 3.8 1.5 7.3 2.9
1.2᎐4.9 2.1᎐7.0 0.3᎐8.2 2.9᎐18.4 0.2᎐47.8
References w1x Musaiger AO. Risk factors for cardiovascular disease in the United Arab Emirates. Int J Food Sci Nutr 1998;49:S65᎐70. w2x Bianco AT, Smilen SW, Davis Y, Lopez S, Lapinski R, Lockwood CJ. Pregnancy outcome and weight gain recommendations for the morbidly obese woman. Obstet Gynecol 1998;91:97᎐102. w3x Edwards LE, Hellerstedt WL, Alton IR, Story M, Himes JH. Pregnancy complications and birth outcomes in obese and normal-weight women: effects of gestational weight change. Obstet Gynecol 1996;87Ž3.:389᎐394. w4x Isaacs JD, Magenn EF, Martin RW, Chauhan SP, Morrison JC. Obstetric challenges of massive obesity complicating pregnancy. J Perinatol 1994;14Ž1.:10᎐14. United States. w5x Robinovich JT, Rubio EL, Saez JC, Ramirez MI. Influence of body weight in pregnancy and the perinatal results. Rev Chile Obstet Ginecol 1995;60Ž3.:151᎐167. Chile. w6x De Groot LC. High maternal body weight and pregnancy outcome. Nutr Rev 1999;57Ž2.:62᎐64. w7x Cnattingius S, Bergstrom R, Lipworth L, Kramer MS. Prepregnancy weight and the risk of adverse pregnancy outcomes. N Engl J Med 1998;338:147᎐152. w8x Johnson JW, Longmate JA, Frentzen B. Excessive maternal weight and pregnancy outcome. Am J Obstet Gynecol 1992;167Ž2.:353᎐370. discussion 370᎐2. w9x Garbaciak Jr. JA, Richter M, Miller S, Barton JJ. Maternal weight and pregnancy complications. Am J Obstet Gynecol 1885;152:238᎐245. w10x Perlow JH, Morgan MA, Montgomery D, Towers CV, Porto M. Perinatal outcome in pregnancy complicated by massive obesity. Am J Obstet Gynecol 1992;167: 958᎐962. w11x Garrow JS. Indices of adiposity. Nutr Abstr Rev Ser 1983;A53:697᎐708.
A.S. Kumari r International Journal of Gynecology & Obstetrics 73 (2001) 101᎐107 w12x Wolfe HM, Zador IE, Gross TL, Martier SS, Sokol RJ. The clinical utility of maternal body mass index in pregnancy. Am J Obstet Gynecol 1991;164:1306᎐1310. w13x Eskenazi B, Fenster L, Sidney S. A multivariate analysis of risk factors for pre-eclampsia. J Am Med Assoc 1991;266:237᎐241.
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w14x Wolfe HM. High pre-pregnancy body-mass index-a maternal-fetal risk factor. N Engl J Med 1998;338Ž3.: 191᎐192. w15x Naeye RL. Maternal body weight and pregnancy outcome. Am J Clin Nutr 1990;52:273᎐279.
Article
Pregnancy outcome in women with morbid obesity A.S. KumariU Department of Obstetrics and Gynecology, Al-Mafraq Hospital, Abu Dhabi, United Arab Emirates Received 30 June 2000; received in revised form 22 November 2000; accepted 29 November 2000
Abstract Objecti¨ e: To study the effects of morbid obesity defined as a first trimester maternal body mass index of ) 40 on the perinatal outcome. Methods: One hundred and eighty-eight singleton pregnancies of women with first trimester BMI ) 40 who delivered at Al-Mafraq Hospital, Abu Dhabi during 1996᎐1998 were studied. A control group of normal body mass index matched for age and parity were selected and the perinatal variables were compared between groups. Morbidly obese women with diabetes and hypertension antedating the index pregnancy were later excluded and the data were re-analyzed. Results: Morbidly obese women were noted to have significantly adverse perinatal outcomes including hypertensive disorders of pregnancy Ž28.8 vs. 2.9%, P- 0.0001., gestational diabetes Ž24.5 vs. 2.2%, P - 0.0001., cesarian section Ž15.2 vs. 9.3%, P- 0.05. and macrosomia Ž32.6 vs. 9.3%, P- 0.001. compared to non-obese women. However, we noted a significantly lower rate of prematurity in the obese group Ž0.5 vs. 5.3%, P- 0.001.. Even when morbidly obese women with Ža. diabetes and hypertension antedating the index pregnancy and Žb. those who developed gestational diabetes andror pregnancy-induced hypertension during the index pregnancy were excluded from the analysis, significant differences in the perinatal outcomes still persisted. Conclusion: Morbid obesity appears to be an independent risk factor for adverse perinatal outcome. 䊚 2001 International Federation of Gynecology and Obstetrics. All rights reserved. Keywords: Morbid obesity; Pregnancy; Perinatal outcome; Gestational diabetes; Macrosomia
1. Introduction During the past 3 decades United Arab Emirates ŽUAE., like all other Gulf States has experienced drastic changes in socio-economic conditions and food habits. These changes have an U
Al-Mafraq Hospital, Department of Obstetrics and Gynecology, P.O. Box 2951, Abu Dhabi, United Arab Emirates. Fax: q971-258-21549. E-mail address: [email protected] ŽA.S. Kumari..
immense influence on the lifestyles and disease patterns in this region. Obesity, a non-communicable disease has assumed an epidemic proportion. While obesity has been established as a risk factor for diabetes mellitus, hypertension, coronary artery disease and stroke, much less is known about the risks of maternal obesity on perinatal outcomes. The 1992 UAE National Nutrition survey w1x based on body mass index revealed that 33% of married women were overweight and 38% were obese. Since age and parity pre-dispose to
0020-7292r01r$20.00 䊚 2001 International Federation of Gynecology and Obstetrics. All rights reserved. PII: S 0 0 2 0 - 7 2 9 2 Ž 0 0 . 0 0 3 9 1 - X
102
A.S. Kumari r International Journal of Gynecology & Obstetrics 73 (2001) 101᎐107
obesity, it is not a surprise that the age-adjusted obesity rate in females exceeds that in males. This trend is particularly prevalent in the Gulf States where a prolonged reproductive span starting in early teens and extending into late forties leads to high parity. All these factors have led to a large numbers of grossly obese women requiring obstetric services. Several publications suggest the adverse effects of obesity on the perinatal outcome. The literature has reported increased incidence of gestational diabetes mellitus ŽGDM., pregnancy-induced hypertension ŽPIH., macrosomia, intrauterine growth retardation, operative deliveries and perinatal mortality w2᎐9x. The complications of anesthesia and surgery in obese individuals are well known and include: difficulties in intubation and ventilation; prolonged operative time; increased blood loss; post-operative infection; and deep venous thrombosis. However, other studies have concluded that obesity by itself is not an independent risk factor for adverse perinatal outcome w10x. This controversy is related to the variance in the definition of obesity, varied population sample size and inadequate control of confounding factors. Obesity is commonly defined in terms of body mass index ŽBMI. ŽWrH 2 . or as a percentage of ideal body weight determined from actuarial tables. It has been defined as a body weight of above 80᎐135 kg, a weight 50᎐300% more than ideal pre-pregnancy weight and a BMI of 30 and above. These varying definitions among different populations make comparison of results difficult. BMI has been used in large population surveys for prevalence of obesity. For the purpose of our study we used Garrow’s grading of obesity based on the Quetlet index or BMI which is weight in kgrheight in m2 w11x. Grade 0 Žnormal. 1 Žoverweight. 2 Žobese. 3 Žmorbidly obese.
BMI wkgrm2 x; 20᎐24.9; 25᎐29.9; 30᎐40; ) 40.
The objective of this study was to determine if pregnant women with grade 3 obesity are at higher
risk of adverse perinatal outcomes than non-obese women.
2. Materials and methods A retrospective study was conducted at the maternity unit of Al-Mafraq hospital, Abu-Dhabi, United Arab Emirates comparing morbidly obese and non-obese women who delivered a singleton between 1996 and 1998. All women who attended the antenatal clinic with a weight of 90 kg and above during the first 12 weeks of pregnancy were selected and their BMI calculated. Women with BMI equal to or more than 40 were included in the study group. When women delivered more than once during the study period only the first pregnancy was used for analysis. Women with first trimester weight - 70 kg and a BMI between 22 and 28, matched for age and parity and who delivered within the fortnight preceding or following the index pregnancy served as controls Žnon-obese group.. The senior charge nurse of the labor and delivery unit collected the data of the control group and was totally blinded to the outcomes of the morbidly obese group. The complete data regarding maternal variables, medical disorders, peripartum and neonatal complications were obtained from delivery room records and prospectively entered into computerized forms. Any missing information was obtained by review of patient’s personal charts. The incidence of selected maternal, peripartum and neonatal outcomes were analyzed in the two groups. The maternal variables studied included age, parity and BMI. Pre-existing medical disorders studied included chronic hypertension and diabetes mellitus. The antepartum variables analyzed were gestational diabetes, pregnancyinduced hypertension, placenta previa, abruption and intrauterine growth retardation. Intrapartum variables studied were shoulder dystocia, cesarian section and preterm labor. The neonatal variables examined were low birth weight Ž- 2500 g., macrosomia Žbirth wt.) 4000 g., low Apgar scores Ž- 7 at 1 min., neonatal intensive care unit ŽNICU. admissions and stillbirths. In order to exclude the influence of medical
A.S. Kumari r International Journal of Gynecology & Obstetrics 73 (2001) 101᎐107
disorders antedating the index pregnancy on the obstetric outcome, morbidly obese women with a diagnosis of chronic hypertension andror diabetes antedating pregnancy were excluded and the outcome variables were re-analyzed. To assess the independent influence of morbid obesity on perinatal outcome, a sub-analysis of morbidly obese women without gestational diabetes and pregnancy-induced hypertension was made. The statistical analysis was performed by using 2 test, odds ratios and 95% confidence intervals were calculated and the significance was defined as P- 0.05.
3. Results One hundred and eighty-eight morbidly obese women and 300 non-obese women matched for age and parity were compared. The maternal demographic variables of each group are presented in Table 1. The antenatal variables are given in Table 2. A significantly higher rate of gestational diabetes Ž P- 0.001. and pregnancyinduced hypertension Ž P- 0.001. was noted in the morbidly obese women as compared to the non-obese group. No significant differences were noted among the groups as regards placental complications and IUGR. Selected intrapartum variables are shown in Table 3. A significantly higher cesarian section rate was seen in the morbidly obese group as compared to the non-obese group Ž P- 0.001., mainly because the obese women had a higher elective cesarian section rate Ž9.6 vs. 3%.. Surprisingly, a lower rate of prematurity was noted in the morbidly obese group Ž P- 0.001. inspite of higher rate of pregnancy-induced hypertension. Table 4 illustrates the neonatal variables. Neonates born to morbidly obese women exhibited a high rate of macrosomia Ž P0.001. and a higher rate of admission to NICU as compared to the non-obese group. The rate of small for gestational age ŽSGA. neonates, although less in the obese group as compared with non-obese group Ž1.6 vs. 5.3%. did not attain statistical significance Ž P- 0.1.. There was a higher rate of stillbirths among morbidly obese women as compared with the non-obese women
103
Table 1 Maternal variables Parameters
Obese Ž n s 188.
Non-obese Ž n s 300.
Age Žyears.
31.66" 5.79 Ž16᎐45. 5.49" 2.46 Ž1᎐13. 44.05" 3.99 Ž40᎐56.
31.78" 5.58 Ž16᎐46. 5.38" 2.52 Ž1᎐13. 25.13" 3.26 Ž22᎐28.
Parity BMI Žkgrm2 .
Ž3.2 vs. 0.7%. but did not reach statistical significance Ž P- 0.06.. Twenty-nine women among the morbidly obese group had diabetes mellitus andror chronic hypertension antedating pregnancy. These were excluded from the study group and the data were re-analyzed. The results are illustrated in Table 5. The increased rates of pregnancy-induced hypertension, gestational diabetes, cesarian section and macrosomia persisted even after controlling for medical complications. Among the morbidly obese group 97 women did not develop gestational diabetes andror pregnancy-induced hypertension. The perinatal outcome in this group is illustrated in Table 6. Significantly higher rates of cesarian section, macrosomia and NICU admissions were noted in these women.
4. Discussion As suggested by Garrow w11x a BMI of 40 and above was used to define morbid obesity. The BMI was calculated from the weight taken during the first antenatal visit before 12 weeks of pregnancy. This BMI reflects pre-pregnancy BMI, since the majority of women during the first trimester lose rather than gain weight. The mean BMI of the control group was 25.13 which was marginally above the normal weight range thus, the non-obese group is composed of women with normal BMI and overweight women. Wolfe et al. w12x reported that both BMI and simple gravid weight comparably predicted the outcome variables in obese pregnant women.
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Table 2 Antenatal variables Variables
Diabetes Total Antedating pregnancy Gestational diabetes Chronic hypertension Pregnancy-induced HTN Placenta previa Abruptio placenta IUGR
Obese Ž n s 188. No. Ž%.
Non-obese Ž n s 300. No. Ž%.
P value
Odds ratio
95% confidence interval
68 Ž36.2. 24 Ž12.8. 44 Ž23.4. 8 Ž4.3. 54 Ž28.7. 1 Ž0.5. 1 Ž0.5. 2 Ž1.0.
8 Ž2.5. 4 Ž1.3. 4 Ž1.3. 1 Ž0.3. 9 Ž3.0. 2 Ž0.7. 1 Ž0.3. 3 Ž1.0.
- 0.0001 - 0.0001 - 0.0001 - 0.1 NS - 0.001 NS NS NS
20.7 10.8 22.6 13.3 3.0 0.8 1.6 1.1
9.6᎐44.3 3.7᎐31.7 8.0᎐64.1 1.6᎐107 6.2᎐27 0.1᎐8.8 0.1᎐25 0.2᎐6.4
Since our population is multiracial and multiethnic with different anthropometric standards we chose BMI rather than simple weight measurements to define morbid obesity. As noted in the literature w4,5,9,10x there was significantly higher frequency of diabetes mellitus antedating pregnancy in morbidly obese women when compared to the non-obese group Ž12.8 vs. 1.3%.. Compared to the literature, the rate of chronic hypertension in the study group was low Ž4.3%. probably reflecting racial differences. There was a significantly higher rate of gestational diabetes in the obese group Ž25.8 vs. 1.3% in the non-obese group.. This rate is higher than that reported by other studies w2,3,10x. This discrepancy could be due to the overall higher prevalence of diabetes mellitus in the Gulf countries w1x. Concordant to the literature w2,3,10,13x, there was a significantly higher occurrence of
pre-eclampsia in the morbidly obese group Ž28.7 vs. 3%.. This high rate persisted even when women with diabetes and hypertension antedating pregnancy were excluded from analysis Ž25.8 vs. 3%.. The cesarian section rate in the morbidly obese group was significantly higher Ž19.1 vs. 9.3%. and was contributed mainly by the higher elective cesarian section rate of 9.6% compared to only 3% in the non-obese group. Fifty percent of the cesarian sections of the obese group and 32% in the non-obese group were elective due to the presence of a combination of factors like inadequately controlled diabetes, hypertension, macrosomia, previous shoulder dystocia and failure of induction. The emergency sections were done mostly for arrest disorders. These results are consistent with many previous reports w2᎐5,8,9x. These differences persisted even when pre-existing diabetic and hypertensive women were excluded from
Table 3 Intrapartum variables Parameters
Cesarian section Elective Emergency Total Preterm delivery Shoulder dystocia
Obese Ž n s 188. No. Ž%.
Non-obese Ž n s 300. No. Ž%.
P value
Odds ratio
95% confidence interval
18 Ž9.6. 18 Ž9.6. 36 Ž19.1. 1 Ž0.5. 4 Ž2.1.
9 Ž3.0. 19 Ž6.3. 28 Ž9.3. 16 Ž5.3. 2 Ž0.7.
- 0.01 - 0.2 - 0.001 - 0.001 - 0.2
3.4 1.6 2.3 0.1 3.2
1.5᎐7.8 0.8᎐3.1 1.4᎐3.9 0.01᎐0.7 0.6᎐17.7
A.S. Kumari r International Journal of Gynecology & Obstetrics 73 (2001) 101᎐107
105
Table 4 Neonatal variables Obese Ž n s 188. No. Ž%.
Non-obese Ž n s 300. No. Ž%.
P-value
Odds ratio
95% confidence interval
Birth weight ) 4000 g - 2500 g Low apgar Ž- 7 at 1 min.
58 Ž30.9. 3 Ž1.6. 4 Ž2.1.
31 Ž10.3. 16 Ž5.3. 6 Ž2.0.
- 0.001 0.10 NS - 0.31 NS
3.9 0.3 1.1
2.4᎐6.3 0.1᎐1.0 0.3᎐3.8
NICU admission Still birth
30 Ž16. 6 Ž3.2.
12 Ž4.0. 2 Ž0.7.
- 0.001 - 0.06
4.6 4.9
2.3᎐9.1 1.0᎐24.6
Outcome
analysis. Garbaciak et al. w9x reported similar findings suggesting that obesity per se leads to an increased risk of cesarian section with all its subsequent complications. This contrasts with the study of Parlow et al. w10x who suggested that obesity per se was not associated with higher cesarian section rates. Despite a high rate of pre-eclampsia and gestational diabetes there was a significantly lower rate of preterm labor Ž0.5 vs. 5.3%. among the morbidly obese group. Wolfe w14x also stated that preterm delivery among obese women is half of that in normal women. These results are in contrast to those of Bianco et al. w2x and Cnattingius et al. w7x. Many studies w2,3,8,10x have demonstrated that morbidly obese women are more likely to deliver large for gestational age neonates. The rate of macrosomia among morbidly obese women was higher Ž30.9 vs. 10.3%. than the reported rate in the literature. This could be explained by the high frequency of gestational diabetes among our
women, since it persisted even after controlling for pre-existing diabetes and hypertension. The rate of small for gestational age ŽSGA. neonates was less in the morbidly obese group than in the control group Ž1.6 vs. 5.3%., although this difference did not reach statistical significance. This is consistent with many previous studies w2,6᎐8x and probably suggests the protective role of maternal obesity against birth of SGA infants. The higher incidence of SGA noted in few studies w10x could be related to chronic hypertension and diabetic vasculopathy complicating these pregnancies. Obesity in pregnant women is associated with an increased risk of perinatal mortality w5᎐7,15x. We also noted an increased incidence of stillbirths in the morbidly obese group Ž3.2 vs. 0.7%.. However, majority of these stillbirths were in diabetic women and when these were excluded from analysis there were no significant differences between groups and is in contrast to the study of Cnattingius w7x. Admissions to NICU
Table 5 Perinatal outcome excluding morbidly obese women with diabetes and chronic hypertension antedating pregnancy Outcome
Obese Ž n s 159. No. Ž%.
Non-obese Ž n s 300. No. Ž%.
P-value
Odds ratio
95% confidence interval
Gestational diabetes Pregnancy-induced HTN Cesarian section Macrosomia Still birth
41 Ž5.8. 41 Ž25.8. 26 Ž16.3. 44 Ž27.7. 1 Ž0.6.
4 Ž1.3. 9 Ž3.0. 28 Ž9.3. 31 Ž10.3. 2 Ž0.7.
- 0.001 - 0.001 - 0.001 - 0.001 NS
25.7 11.2 1.9 3.3 0.9
9.0᎐73.4 5.3᎐23.8 1.1᎐3.4 2.0᎐5.5 0.1᎐10.5
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Table 6 Perinatal outcome excluding gestational diabetes and pregnancy-induced hypertension in morbidly obese and non-obese groups Outcome
Cesarian section Emergency Elective Total Macrosomia Low apgar Ž- 7 at 1 min. NICU admission Still birth
Obese Ž n s 97. No. Ž%.
Non-obese Ž n s 285. No. Ž%.
7 Ž7.2. 8 Ž8.2. 15 Ž15.4. 26 Ž26.8. 2 Ž2.1. 15 Ž15.5. 1 Ž1.0.
7 Ž2.5. 13 Ž4.5. 20 Ž7.0. 25 Ž8.8. 4 Ž1.4. 7 Ž2.5. 1 Ž0.4.
were more frequent in the morbidly obese group Ž16 vs. 4%. and were contributed mainly by macrosomic infants. Since GDM and PIH may be the causal mechanisms for adverse perinatal outcomes in morbidly obese women w7x, many of the studies have not controlled for these variables in their analysis. In our study, in the sub-group of morbidly obese women after controlling for GDM and PIH, we still noted higher rates of cesarian section Ž15.4 vs. 7%., macrosomia Ž26.8 vs. 8.8%. and NICU admissions Ž15.5 vs. 2.5%.. Bianco et al. w2x noted high rate of macrosomia in their study after controlling only for gestational diabetes. This probably suggests that obesity can cause sub-optimal perinatal outcome through mechanisms other than GDM and PIH. From the results it appears that morbid obesity is an independent risk factor for adverse perinatal outcomes. Maternal obesity may be one of the most important preventable risk factors for perinatal mortality. Prenatal counseling of obese women regarding weight reduction and healthy food habits seems vital. The excessive weight gain during pregnancy above the recommended standards in the Arabian Gulf women w1x and the high parity contributes to progressive obesity and its consequent risks. In the morbidly obese pregnant women, the effects of dietary interventions in modifying adverse perinatal outcomes are not yet proven. Every effort should be made to prevent increasing body weight and encourage women to return to pre-pregnancy weight and reach a normal body mass index before the next pregnancy.
P-value
Odds ratio
95% confidence interval
- 0.04 - 0.001 0.6 - 0.001 0.62
2.4 3.8 1.5 7.3 2.9
1.2᎐4.9 2.1᎐7.0 0.3᎐8.2 2.9᎐18.4 0.2᎐47.8
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