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Serum lipid studies in pregnancy
Serum lipid studies in pregnancy S.
MULLICK,
M.B.,
0.
P.
M.D.
V.
Du
New
BAGGA, MULLICK,
Delhi,
B.S.,
M.B.,
M.Sc.
B.S.,
PH.D.
India
I N 1 8 4 5 Bacquerol and Kodier recognized that there was an increase in blood lipids during pregnancy.r Henson attributed the hyperlipemia to greater fat absorption, while Puzos ascribed it to mixing of blood with the milk for nutrition of the fetus, according to Boyd.?, 3 Chauffard4 undertook the first chemical study and suggested that an increase occurs in the cholesterol level, but Bloo? failed to confirm the presence of hypercholesterolemia. With the development of more modern techniques, detailed analytical studies were undertaken by various workers including DieckmanG Schwarz,? Peters,’ Von Studnitz,’ Watson,l” and de Alvarez.ll Boydl” commented on the great variation in the data of different workers. Although almost all observed an increase in total lipids during the third trimester, the increase was neither consistent in time of appearance nor proportion of changes in the various fractions. The present investigations were undertaken to define more precisely the changes in total lipids and their fractions during different periods of gestation and, also, if possible, to analyze the factors which bring about these changes. Methods
and
group was subjected to the following analysis for the establishment of normal values. 1. Total lipids.13 2. Total cholestero1.l.‘. I5 3. Free cholestero1.14, ‘j 4. Phospholipids.l’, I7 5. Lipoprotein distribution.ls The blood was collected in the postabsorptive period, 4 to 5 hours after a light breakfast. In the second stage the sera of 60 normal pregnant women attending the antenatal clinic of Lady Hardinge Medical College and Hospital were analyzed for lipids, total cholesterol, free cholesterol, phospholipid, and lipoproteins. In the patient’s history special attention was paid to customs, socioeconomic status, and duration of pregnancy. No patient was included if any abnormality occurred during pregnancy. Two patients were studied serially throughout pregnancy and one was followed 4 weeks post partum. Observations
On general analysis of the data it was observed that the levels of serum lipid and its fractions bear a relationship to the socioeconomic status of the subject, which may be a reflection of the dietary fat ingested. Therefore, the data were divided into two groups. Group A. This group was composed of patients with a high economic status-a family income of 500 to 1,000 rupees or more a month. The women included in this group were physicians. All were nonvege-
materials
The present study was made in two phases. In the first stage, serum of 20 healthy nonpregnant women in the 18 to 35 years age
From Lady
the
Department Medical
Hardinge
of Physiology, College.
766
Volume Number
89 6
Table
Total cholesterol (w %)
serum lipids (mg. %) A, nonvegetarians
Range 380 to 760 Average 606.0 Group
II. Serum
Free cholesterol (mg. %)
Ester cholesterol (mg. %)
Phospholipid (mg. %)
Lipoproteins p/a ratio
35.5 to 75.3 56.0
102 to 158 129.5
216.25 to 259.50 241.44
2.7: 1
150.0 to 200 171.04
40.8 to 69.5 49.16
100 to 146.7 121.9
209.25 to 233.75 214.08
2.47: I
148.8 to 200.3 168.8
42.2 to 50.3 45.5
106.6 to 150 123.0
215 to 234.5 224.0
2.24: 1
lipid
analysis
during
pregnancy
Total cholesterol (w. %)
Free cholesterol (w. %)
Ester cholesterol (mg. %)
Phospholipid (mg. %I
Lipoprotein /3/a ratio
trimester
Vegetarians Nonvegetarians Second trimester Vegetarians Nonvegetarians Third
767
143.6 to 233.3 192.0
Total serum lipids (mg. %) First
in pregnancy
B
Vegetarians Range 420 to 520 Average 456.60 Nonvegetarians Range 420 to 480 Average 430.0
Table
lipid
I
Total Group
Serum
565.70 515.00
185.65 183.20
51.39 50.27
130.52 133.22
133.18 234.56
2.89: 1 2.95 : 1
712.0 675.0
225.50 222.13
63.09 62.16
163.60 160.10
254.80 245.03
3.11:1 2.91: 1
813.84 814.54
249.46 254.73
67.31 70.11
181.53 184.44
257.09 266.50
3.51: 1 3.33 : I
trimester
Vegetarians Nonvegetarians
tarians and their average intake per day was 200 -to 250 Gm. carbohydrate; 70 to 90 Gm. fats; and 75 to 100 Gm. of proteins. Meat ingestion once a day was a regular feature with some, while others ate meat only three to four times a week. One egg a day was common to all. Group B. This group was composed of families with low socioeconomic status-a family income of 100 to 499 rupees a month. The women included in this group were ayas, midwives, and attendants of patients. In this group 11 were vegetarians and 9 were nonvegetarians. The average daily intake of vegetarians was 250 to 300 Gm. of carbohydrates, 40 to 50 Gm. of proteins, especially pulses and beans. The nonvegetarians of this group, although they had no religious or mental aversion to animal proteins, ate meat only once a week or once a fortnight.
Similarly, ingestion of eggs was infrequent. The intake of proteins and fats was nearly the same except for carbohydrates which was slightly less. The values obtained in 11 healthy nonpregnant nonvegetarians of Group A are given in Table I. These values compare well with the reports of Boyd12 but were somewhat lower than the figures of de Alvarez.ll The averages for Group B composed of vegetarians and nonvegetarians (Table I) were much lower than for Group A. Even between the vegetarians and nonvegetarians there was some variation-the total lipids being 15.8 per cent higher in Group A. The results for the pregnant patients were further divided into three groups, according to period of gestation, vegetarians, and nonvegetarians.
768
Mullick,
Table
III.
Bagga,
Serum
of
Period
and
lipids
gestation
Mullick
during Total (mg.
third lipids %)
trimester
and post partum
~~~~
; --~~ij:;I--~-c~~~;
Thirty-sixth week Fortieth week Fourth day post partum
800.0 900.0 900.0
309.5 379.0
Fourth ..___
860.0
290.0
week
Group
post partum
264.0
I. These patients in the first triincluded 18 pregnant women between the ages of 20 and 30. All but 4 were vegetarians and had no clinical abnormality. The group as a whole falls into the low income range. The values found are shown in ‘I’able II. First trimester. Comparison of the data on the first trimester determinations with the values for the nonpregnant females of Group T% shows that there is a marked increase in the average of total lipids in both vegetarians and nonvegetarians, and a perceptible rise in total cholesterol and phospholipids. ‘[‘he increase occurred during the first 8 weeks (25 per cent in vegetarians and 20 per cent increase in nonvegetarians). During the subsequent 4 weeks there was a slight fall, yet the values remained 18 to 23 per cent above normal. The range and the average of total cholesterol at the end of first trimester both in vegetarians and nonvegetarians was above normal. However, tota cholesterol, like serum lipids, did not show a rise in the first 8 weeks but instead showed a decline. The fall was 3 per cent in vegetarians and 2 per cent in nonvegetarians. The fall was followed by a persistent but a gradual rise. By the twelfth week it was 8.2 per cent above the average figure for vegetarians and 8.9 per cent for the nonvegetarians. Free cholesterol, cholesterol ester, and phospholipid were observed to follow the pattern for total cholesterol. The rise in cholesterol ester and free cholesterol was nearly proportionate, both in vegetarians and nonvegetarians, but the phospholipid fraction registered a greater increase in vegetarians than nonvegetarians. The rise was 8.98 per cent in the former and 4.3 per cent rnester
70.7 70.8 106.7 96.3
~ p~,:~‘~d;~il 193.3 “x3.7 273.3 193.5
“52.00 ‘0.k.30 ‘7.f.75 ‘2-4L’.5 ( I
in the latter. The beta lipoproteins of the serum also increased and the ratio of beta: alpha lipoprotein was much above the control series. Second trimester. This group consisted of 18 normal healthy females in the second trimester of pregnancy. All were multiparas except 3. Eleven were vegetarians and sewers nonvegetarians. The values of serum lipid analysis of both vegetarians and non\~egctarians have been shown in Table I. In general there was a marked increase over nonpregnant values in all the lipid fractions in both the groups. The avcrage of total serum lipid in vegetarians touched the figure of 712 mg. per cent against that of 565.70 mg. per cent of first trirnester, and in nonvegetarians it Lvas 675 mg. against that of 515 mg. per cer!i. These values were 56.2 and 57 per cent above the respective contr,ol values. ‘I’ll? increase in total cholesterol and its fraction was parallel to the rise in s~r~tm trrtal lipids. The cholesterol increased 1,) 31 .6 per writ above the control group in vegetarians and by 31.07 per cent in nonvegetarians. The ester and free cholesterol fraction shoxvrtl a rise in xregetarians by 33 per cent and 28.5 per cent above tlleir control scric,s. The nonvegetarians recorded a similar rist‘. It was 30 per cent in ester cholesterol and 37.8 per cent in free cholestcx)l. The phospholipids showed an increase INI t this was not proportionate to the risr in cholestrrol or serum lipids. ‘I’h(* increast, \~a\ 18.7 per cent in \,egetarians and 9.38 per cent in nonvegetarians. A similar rise, occurred in beta/alpha lipoprotein ratio. Third trimester. The group included 24 ht,althy gravidas in the third trimester. Eleven were non\.eg:etarians and 13 LY!,~v-
Serum
tarians. The results of various analyses given in Table I showed that the total serum lipids increased markedly in both the groups in comparison to the values obtained from those of the first and second trimester and of the control group. In vegetarians the increase above the control in total lipid was 78.3 per cent and in total cholesterol, free cholesterol, ester cholesterol, and phospholipid was 48.9 per cent, 36.9 per cent, 48.33 per cent, and 20.1 per cent, respectively. The nonvegetarians series showed similar increases. This amounted to 78.3 per cent in total lipids and 52.1 per cent in total cholesterol. Free cholesterol was 54.1 per cent, whereas ester cholesterol was 49.99 per cent. Phospholipids were slightly lower among the vegetarians in the third trimester but were higher than for the control group of nonvegetarians. One subject, S. K., who was a vegetarian and of low income group was followed 4 weeks post partum. The lipid determinations were also made at the thirty-sixth and fortieth week of pregnancy. These values are shown in Table III. It can be seen that after termination of *“pregnancy the serum lipid and its fractions do not suddenly decline but instead they increase for some time. Even 4 weeks after delivery the values are much above the normal. Comment In the healthy female serum lipid level and its fractions vary with the nutritional status which is dependent on the socioeconomic condition of the individual. Values for the high income group are close to those reported by B0yd.l” The data for both vegetarians and nonvegetarians of the low income group gave lower average figures. The comparison of the figures for vegetarians and nonvegetarians revealed that the avera
lipid
in pregnancy
769
to explain how an occasional interruption in this regime by food of animal origin could cause such an appreciable difference. The analysis of the series of pregnant women shows that a tiansient increase in total serum lipids occurs in the first 8 weeks of the first trimester and that this is followed by a slight fall. The increase is more marked in the vegetarians than in the nonvegetarians. The total serum cholesterol, ester cholesterol, and free cholesterol showed the reverse trend. A similar pattern of change was observed by de Alvarez,ll but he attached no importance to it. In the second trimester the rise in serum lipids, total cholesterol and phospholipids was consistent and proportionate. De Alvarez,ll and Boyd,‘? observed similar changes. However when the mean value of the serum lipid of the vegetarian was compared with that of the nonvegetarian, it was observed that the differences observable in the first trimester has been narrowed. During the third trimester there was a further increase in the levels of the serum lipid and its fractions. When the figures for the nonvegetarians were compared with those of the vegetarians there was no difference in the total serum lipid values, but there was now a slight increase for the former (Table I). From this it may be concluded that diet has no significant influencr on lipid synthesis in the later period of precnancy. In 1959 de Alvarez’l reported that the increase in serum lipids occurs at the end of the second trimester and Peters, Hcinmann, and Man”’ r,ecorded a rise in the early part of this trimester. Watsonl” noted that the hyperlipemia increases to the twenty-ninth week and that, thereafter, a constant level is maintained. In the present study, both in vegcttarians and nonvcgetarians, the increase was noticed as early as the end of the first trimester and the riyc continued throughout the pregnancy. How is this lipemia brought about and what purpose it serves is the crux of the problem. Since the influence of diet in the present series, especially in the second and
770
Muilick,
Bagga,
and
Mullick
third trimester, seems to have been rather slight, the influence of hormones should be considered. An increase in the various hormones during gestation and their influence on blood lipids is well established. Estrogens when administered cause a fall in serum lipids and its partitions with a rise in alpha lipoproteins (Adlersberg) .‘I Thyroxin, like estrogens depresses the blood lipids. Cortisone increases the cholesterol and its ester level and this is achieved at the cost of the neutral fats (JaileP). Somatotrophic hormone of the anterior pituitary raises the blood lipid level and lipid mobilizer hormone of the posterior pituitary aids the process of lipogenesis by mobilizing the depot fat.‘3
Summary
1. The total serum lipids, total cholesterol, free cholesterol, phospholipid, and lipoprotein ratio were first studied in control groups of nonpregnant women of high and low socioeconomic levels. 2. The behavior of various lipid fractions during different periods of gestation were then studied in the 62 normal gravid women. 3. All the lipid fractions show a gradual and persistent rise throughout pregnancy among both the vegetarians and nonvegetarians. 4. The increase in serum lipids continues even after the termination of pregnancy.
REFERENCES
I.
De
Alvarez, R. R., et al.: AM. J. OBST. & 77: 743, 1959. Boyd, E. M.: J. Clin. Invest. 13: 347, 1934. Boyd, E. M.: J. Clin. Invest. 13: 347, 1934. De Alvarez, R. R., et al.: AM. J. OBST. & GYNEC. 77: 743, 1959. Bloor, W. R.: J. Biol. Chem. 49: 201, Die&man, W.-I., and Wegner, C. RI: Arch. Int. Med. 53: 540. 1934. Schwarz, 0. H.: Au. J. OBST. & GYNEC. 39: 203, 1940. Peters, J. P., and Man, E. B.: J. Clin. Invest. 22: 707, 1943. Von Studnitz, W.: Scandinav. J. Clin. & Lab. Invest. 7: 329, 1955. Watson, W. C.: Clin. SC. 16: 475, 1957. De Alvarez, R. R., Gaiser, D. F., Simkins, D. M., Smith, E. K., and Bratvold, G. E.: AM. J. OBST. & GYNEC. 77: 743, 1959. Boyd, E. M.: J. Clin. Invest. 13: 347, 1934.
13.
GYNEC.
2. 7 4. 5. 6. 7. 8. 9. 10. 11.
12.
14. 15. 16. 17. 18. 19. 20. 21. 22. 23.
Sperry, W. M., and Brand, F. C.: J. Biol. Chem. 213: 69. 1955. Sperry, W. M.,‘and Webb, M.: J. Biol. Chem. 187: 97, 1950. Schoenheimer, R., and Sperry, W. M.: J. Biol. Chem. 106: 745, 1934. Youngburg, G. E., and Youngburg, M. V.: 1. Lab. & Clin. Med. 16: 158. 1930. Fiske, C. H., and Subbarow: Y.: J. Biol. Chem. 66: 375, 1925. Jencks, W. P.,. Jetton, M. R., and Durrurn,. E. L.: T. Clin. Invest. 35: 1437. 1955. Boyd, l?. M.: J. Biol. Chem. 14i: 131, 1942. Peters, J. P., Heinemann, M., and Man, E. B.: J. Clin. Invest. 30: 388, 1951. Adlersberg, D.: Am. J. Med. 23: 769, 1957. Jailer, J. W., and Longson, D.: Clin. North America 37: 341, 1957. Seifter, J., and Beader, D. H.: Proc. Sot. Exper. Biol. & Med. 95: 318, 1957.
MULLICK,
M.B.,
0.
P.
M.D.
V.
Du
New
BAGGA, MULLICK,
Delhi,
B.S.,
M.B.,
M.Sc.
B.S.,
PH.D.
India
I N 1 8 4 5 Bacquerol and Kodier recognized that there was an increase in blood lipids during pregnancy.r Henson attributed the hyperlipemia to greater fat absorption, while Puzos ascribed it to mixing of blood with the milk for nutrition of the fetus, according to Boyd.?, 3 Chauffard4 undertook the first chemical study and suggested that an increase occurs in the cholesterol level, but Bloo? failed to confirm the presence of hypercholesterolemia. With the development of more modern techniques, detailed analytical studies were undertaken by various workers including DieckmanG Schwarz,? Peters,’ Von Studnitz,’ Watson,l” and de Alvarez.ll Boydl” commented on the great variation in the data of different workers. Although almost all observed an increase in total lipids during the third trimester, the increase was neither consistent in time of appearance nor proportion of changes in the various fractions. The present investigations were undertaken to define more precisely the changes in total lipids and their fractions during different periods of gestation and, also, if possible, to analyze the factors which bring about these changes. Methods
and
group was subjected to the following analysis for the establishment of normal values. 1. Total lipids.13 2. Total cholestero1.l.‘. I5 3. Free cholestero1.14, ‘j 4. Phospholipids.l’, I7 5. Lipoprotein distribution.ls The blood was collected in the postabsorptive period, 4 to 5 hours after a light breakfast. In the second stage the sera of 60 normal pregnant women attending the antenatal clinic of Lady Hardinge Medical College and Hospital were analyzed for lipids, total cholesterol, free cholesterol, phospholipid, and lipoproteins. In the patient’s history special attention was paid to customs, socioeconomic status, and duration of pregnancy. No patient was included if any abnormality occurred during pregnancy. Two patients were studied serially throughout pregnancy and one was followed 4 weeks post partum. Observations
On general analysis of the data it was observed that the levels of serum lipid and its fractions bear a relationship to the socioeconomic status of the subject, which may be a reflection of the dietary fat ingested. Therefore, the data were divided into two groups. Group A. This group was composed of patients with a high economic status-a family income of 500 to 1,000 rupees or more a month. The women included in this group were physicians. All were nonvege-
materials
The present study was made in two phases. In the first stage, serum of 20 healthy nonpregnant women in the 18 to 35 years age
From Lady
the
Department Medical
Hardinge
of Physiology, College.
766
Volume Number
89 6
Table
Total cholesterol (w %)
serum lipids (mg. %) A, nonvegetarians
Range 380 to 760 Average 606.0 Group
II. Serum
Free cholesterol (mg. %)
Ester cholesterol (mg. %)
Phospholipid (mg. %)
Lipoproteins p/a ratio
35.5 to 75.3 56.0
102 to 158 129.5
216.25 to 259.50 241.44
2.7: 1
150.0 to 200 171.04
40.8 to 69.5 49.16
100 to 146.7 121.9
209.25 to 233.75 214.08
2.47: I
148.8 to 200.3 168.8
42.2 to 50.3 45.5
106.6 to 150 123.0
215 to 234.5 224.0
2.24: 1
lipid
analysis
during
pregnancy
Total cholesterol (w. %)
Free cholesterol (w. %)
Ester cholesterol (mg. %)
Phospholipid (mg. %I
Lipoprotein /3/a ratio
trimester
Vegetarians Nonvegetarians Second trimester Vegetarians Nonvegetarians Third
767
143.6 to 233.3 192.0
Total serum lipids (mg. %) First
in pregnancy
B
Vegetarians Range 420 to 520 Average 456.60 Nonvegetarians Range 420 to 480 Average 430.0
Table
lipid
I
Total Group
Serum
565.70 515.00
185.65 183.20
51.39 50.27
130.52 133.22
133.18 234.56
2.89: 1 2.95 : 1
712.0 675.0
225.50 222.13
63.09 62.16
163.60 160.10
254.80 245.03
3.11:1 2.91: 1
813.84 814.54
249.46 254.73
67.31 70.11
181.53 184.44
257.09 266.50
3.51: 1 3.33 : I
trimester
Vegetarians Nonvegetarians
tarians and their average intake per day was 200 -to 250 Gm. carbohydrate; 70 to 90 Gm. fats; and 75 to 100 Gm. of proteins. Meat ingestion once a day was a regular feature with some, while others ate meat only three to four times a week. One egg a day was common to all. Group B. This group was composed of families with low socioeconomic status-a family income of 100 to 499 rupees a month. The women included in this group were ayas, midwives, and attendants of patients. In this group 11 were vegetarians and 9 were nonvegetarians. The average daily intake of vegetarians was 250 to 300 Gm. of carbohydrates, 40 to 50 Gm. of proteins, especially pulses and beans. The nonvegetarians of this group, although they had no religious or mental aversion to animal proteins, ate meat only once a week or once a fortnight.
Similarly, ingestion of eggs was infrequent. The intake of proteins and fats was nearly the same except for carbohydrates which was slightly less. The values obtained in 11 healthy nonpregnant nonvegetarians of Group A are given in Table I. These values compare well with the reports of Boyd12 but were somewhat lower than the figures of de Alvarez.ll The averages for Group B composed of vegetarians and nonvegetarians (Table I) were much lower than for Group A. Even between the vegetarians and nonvegetarians there was some variation-the total lipids being 15.8 per cent higher in Group A. The results for the pregnant patients were further divided into three groups, according to period of gestation, vegetarians, and nonvegetarians.
768
Mullick,
Table
III.
Bagga,
Serum
of
Period
and
lipids
gestation
Mullick
during Total (mg.
third lipids %)
trimester
and post partum
~~~~
; --~~ij:;I--~-c~~~;
Thirty-sixth week Fortieth week Fourth day post partum
800.0 900.0 900.0
309.5 379.0
Fourth ..___
860.0
290.0
week
Group
post partum
264.0
I. These patients in the first triincluded 18 pregnant women between the ages of 20 and 30. All but 4 were vegetarians and had no clinical abnormality. The group as a whole falls into the low income range. The values found are shown in ‘I’able II. First trimester. Comparison of the data on the first trimester determinations with the values for the nonpregnant females of Group T% shows that there is a marked increase in the average of total lipids in both vegetarians and nonvegetarians, and a perceptible rise in total cholesterol and phospholipids. ‘[‘he increase occurred during the first 8 weeks (25 per cent in vegetarians and 20 per cent increase in nonvegetarians). During the subsequent 4 weeks there was a slight fall, yet the values remained 18 to 23 per cent above normal. The range and the average of total cholesterol at the end of first trimester both in vegetarians and nonvegetarians was above normal. However, tota cholesterol, like serum lipids, did not show a rise in the first 8 weeks but instead showed a decline. The fall was 3 per cent in vegetarians and 2 per cent in nonvegetarians. The fall was followed by a persistent but a gradual rise. By the twelfth week it was 8.2 per cent above the average figure for vegetarians and 8.9 per cent for the nonvegetarians. Free cholesterol, cholesterol ester, and phospholipid were observed to follow the pattern for total cholesterol. The rise in cholesterol ester and free cholesterol was nearly proportionate, both in vegetarians and nonvegetarians, but the phospholipid fraction registered a greater increase in vegetarians than nonvegetarians. The rise was 8.98 per cent in the former and 4.3 per cent rnester
70.7 70.8 106.7 96.3
~ p~,:~‘~d;~il 193.3 “x3.7 273.3 193.5
“52.00 ‘0.k.30 ‘7.f.75 ‘2-4L’.5 ( I
in the latter. The beta lipoproteins of the serum also increased and the ratio of beta: alpha lipoprotein was much above the control series. Second trimester. This group consisted of 18 normal healthy females in the second trimester of pregnancy. All were multiparas except 3. Eleven were vegetarians and sewers nonvegetarians. The values of serum lipid analysis of both vegetarians and non\~egctarians have been shown in Table I. In general there was a marked increase over nonpregnant values in all the lipid fractions in both the groups. The avcrage of total serum lipid in vegetarians touched the figure of 712 mg. per cent against that of 565.70 mg. per cent of first trirnester, and in nonvegetarians it Lvas 675 mg. against that of 515 mg. per cer!i. These values were 56.2 and 57 per cent above the respective contr,ol values. ‘I’ll? increase in total cholesterol and its fraction was parallel to the rise in s~r~tm trrtal lipids. The cholesterol increased 1,) 31 .6 per writ above the control group in vegetarians and by 31.07 per cent in nonvegetarians. The ester and free cholesterol fraction shoxvrtl a rise in xregetarians by 33 per cent and 28.5 per cent above tlleir control scric,s. The nonvegetarians recorded a similar rist‘. It was 30 per cent in ester cholesterol and 37.8 per cent in free cholestcx)l. The phospholipids showed an increase INI t this was not proportionate to the risr in cholestrrol or serum lipids. ‘I’h(* increast, \~a\ 18.7 per cent in \,egetarians and 9.38 per cent in nonvegetarians. A similar rise, occurred in beta/alpha lipoprotein ratio. Third trimester. The group included 24 ht,althy gravidas in the third trimester. Eleven were non\.eg:etarians and 13 LY!,~v-
Serum
tarians. The results of various analyses given in Table I showed that the total serum lipids increased markedly in both the groups in comparison to the values obtained from those of the first and second trimester and of the control group. In vegetarians the increase above the control in total lipid was 78.3 per cent and in total cholesterol, free cholesterol, ester cholesterol, and phospholipid was 48.9 per cent, 36.9 per cent, 48.33 per cent, and 20.1 per cent, respectively. The nonvegetarians series showed similar increases. This amounted to 78.3 per cent in total lipids and 52.1 per cent in total cholesterol. Free cholesterol was 54.1 per cent, whereas ester cholesterol was 49.99 per cent. Phospholipids were slightly lower among the vegetarians in the third trimester but were higher than for the control group of nonvegetarians. One subject, S. K., who was a vegetarian and of low income group was followed 4 weeks post partum. The lipid determinations were also made at the thirty-sixth and fortieth week of pregnancy. These values are shown in Table III. It can be seen that after termination of *“pregnancy the serum lipid and its fractions do not suddenly decline but instead they increase for some time. Even 4 weeks after delivery the values are much above the normal. Comment In the healthy female serum lipid level and its fractions vary with the nutritional status which is dependent on the socioeconomic condition of the individual. Values for the high income group are close to those reported by B0yd.l” The data for both vegetarians and nonvegetarians of the low income group gave lower average figures. The comparison of the figures for vegetarians and nonvegetarians revealed that the avera
lipid
in pregnancy
769
to explain how an occasional interruption in this regime by food of animal origin could cause such an appreciable difference. The analysis of the series of pregnant women shows that a tiansient increase in total serum lipids occurs in the first 8 weeks of the first trimester and that this is followed by a slight fall. The increase is more marked in the vegetarians than in the nonvegetarians. The total serum cholesterol, ester cholesterol, and free cholesterol showed the reverse trend. A similar pattern of change was observed by de Alvarez,ll but he attached no importance to it. In the second trimester the rise in serum lipids, total cholesterol and phospholipids was consistent and proportionate. De Alvarez,ll and Boyd,‘? observed similar changes. However when the mean value of the serum lipid of the vegetarian was compared with that of the nonvegetarian, it was observed that the differences observable in the first trimester has been narrowed. During the third trimester there was a further increase in the levels of the serum lipid and its fractions. When the figures for the nonvegetarians were compared with those of the vegetarians there was no difference in the total serum lipid values, but there was now a slight increase for the former (Table I). From this it may be concluded that diet has no significant influencr on lipid synthesis in the later period of precnancy. In 1959 de Alvarez’l reported that the increase in serum lipids occurs at the end of the second trimester and Peters, Hcinmann, and Man”’ r,ecorded a rise in the early part of this trimester. Watsonl” noted that the hyperlipemia increases to the twenty-ninth week and that, thereafter, a constant level is maintained. In the present study, both in vegcttarians and nonvcgetarians, the increase was noticed as early as the end of the first trimester and the riyc continued throughout the pregnancy. How is this lipemia brought about and what purpose it serves is the crux of the problem. Since the influence of diet in the present series, especially in the second and
770
Muilick,
Bagga,
and
Mullick
third trimester, seems to have been rather slight, the influence of hormones should be considered. An increase in the various hormones during gestation and their influence on blood lipids is well established. Estrogens when administered cause a fall in serum lipids and its partitions with a rise in alpha lipoproteins (Adlersberg) .‘I Thyroxin, like estrogens depresses the blood lipids. Cortisone increases the cholesterol and its ester level and this is achieved at the cost of the neutral fats (JaileP). Somatotrophic hormone of the anterior pituitary raises the blood lipid level and lipid mobilizer hormone of the posterior pituitary aids the process of lipogenesis by mobilizing the depot fat.‘3
Summary
1. The total serum lipids, total cholesterol, free cholesterol, phospholipid, and lipoprotein ratio were first studied in control groups of nonpregnant women of high and low socioeconomic levels. 2. The behavior of various lipid fractions during different periods of gestation were then studied in the 62 normal gravid women. 3. All the lipid fractions show a gradual and persistent rise throughout pregnancy among both the vegetarians and nonvegetarians. 4. The increase in serum lipids continues even after the termination of pregnancy.
REFERENCES
I.
De
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