Maternal Weight Change Research Articles

Women who gain more fat during pregnancy may not have bigger babies: implications for recommended weight gain during pregnancy

The correlation between infant birthweight and the amount of fat gained during pregnancy (estimated as the change in maternal weight between 10 weeks gestation and 2-3 weeks postpartum) was studied in 115 healthy, parous, urban Scottish housewives. There was very little correlation between these variables (r = 0.13, falling to r = 0.07 after birthweight was adjusted for initial maternal weight and length of gestation), i.e., women who gained more fat during their pregnancies did not give birth to heavier babies. This suggests that for most women one of the principal effects of increasing food intake during pregnancy may be to increase maternal fat gain rather than promote fetal growth, and that efforts to increase birthweight by encouraging greater weight gain during pregnancy may be unsuccessful.

Developmental toxicity of soman in rats and rabbits

Soman (GD; phosphonofluoridic acid, methyl-,1,2,2-trimethylpropyl ester) is an organophosphate compound with potent anticholinesterase activity. To determine developmental toxicity, soman was administered orally to CD rats on days 6 through 15 of gestation at dose levels of 0, 37.5, 75, 150, or 165 micrograms/kg/day and to New Zealand White (NZW) rabbits on days 6 through 19 of gestation at dose levels of 0, 2.5, 5, 10, or 15 micrograms/kg/day. At sacrifice, gravid uteri were weighed and examined for number and status of implants. Individual fetal body weights and external, visceral, and skeletal malformations were recorded. Mean maternal weight changes, fetal implantation status/litter, fetal weight, and fetal malformations/litter were compared between dose groups. Monitors for maternal toxicity were net body weight change, treatment weight change, mortality, and clinical signs of toxicity such as lethargy, ataxia, and tremors. Maternal rats and rabbits in the high-dose groups exhibited statistically significant increases in toxicity and mortality when compared to controls. There were no significant dose-related effects among dose groups in the prevalence of postimplantation loss, malformations, or in average body weight of live fetuses per litter. There was no evidence of increased prenatal mortality or fetal toxicity in the CD rat or NZW rabbit following exposure to soman, even at a dose that produced significant maternal toxicity.

Some effects of mastectomy on reproductive success in the guinea-pig

Virgin guinea-pigs were mastectomized in two stages between 11 and 18 weeks of age and then mated, starting 19 weeks after final surgery. In the subsequent first pregnancy, the incidence of still-births and neonatal deaths was significantly higher in the mastectomized animals (6 out of 12 mothers (50%) and 14 out of 49 young (29%) compared with intact guinea-pigs (1 out of 15 mothers (7%) and 1 out of 58 young (2%)). There was no significant effect of mastectomy on litter size and weight or on gestation period. The still-born were not significantly different in weight from those born alive. A significant relation was found between maternal weight changes in the period 20 to 5 days before parturition and the occurrence of still-births and neonatal deaths; still-births were associated with a period of reduced weight gain. No effect of mastectomy on the length of the oestrous cycle was apparent but a significant increase in the incidence of non-pregnancy was found. The results provide further evidence that mastectomy influences reproductive success in the guinea-pig and suggest that parturition is a key process affected.

Postpartum changes in maternal weight and body fat depots in lactating vs nonlactating women

Maternal weight and body fat changes were studied in 56 women from delivery to 6 mo postpartum. Six-month weight losses (p less than 0.01) in exclusively breast-feeding (BF), exclusively formula-feeding (FF), and combination breast- and formula-feeding mothers (CF) were 8.30 +/- 0.74, 8.19 +/- 0.96, and 7.22 +/- 0.74 kg respectively; however, only BF experienced a significant change between 3 and 6 mo. Suprailiac and subscapular skinfold thickness decreased over 6 mo (p less than 0.01) with the suprailiac region reflecting a significant feeding-method effect. Increases in triceps fatfold measurements at 3 mo suggest that a temporary redistribution of body fat occurs as the energy stores of pregnancy are mobilized. Lactating mothers consumed more (p less than 0.01) kilocalories (BF, 2055 +/- 435; CF, 2005 +/- 515) than did nonlactating mothers (FF, 1453 +/- 503). Age, parity, and prepregnancy weight exerted significant covariable effects. Results suggest that lactation does play a role in postpartum weight and body fat loss but that the current RDA may be too high to permit such losses.

Calving and maternal body weight change in the reindeer

Calving and maternal body weight change in the reindeer

Effect of energy intake during lactation on nitrogen retention by the sow for 35 days post-weaning

To establish the effect of an Inadequate dietary energy intake during lactation on the repletion of maternal energy and protein stores post-weaning.Forty-two crossbred, multi-parous (parity 2 to 5) sows were randomly assigned to diet on day-1 of lactation based upon ancestry and parity, Diets were (1) high-energy (66.9 MJ/day) and (2) low-energy (33 MJ/day). Lactation diets were prepared with maizestarch and soyabean meal and formulated to provide equal intake of all nutrients except energy during the 28-day lactation. Total daily nutrient intake was achieved in four proportional meals All litters were standardized to nine pigs/litter on day-1 of lactation. On day-14 of lactation, daily milk yield was estimated by the Weight-suckle-welgh method. Sows were weighed on day-1, day-21 and day-28 of 1actation. Maternal weight change was calculated using maternal weight postpartum and at weaning. On day-28 of lactation, ten sows (weight 182 to 258 kg) from each treatment were selected at random and assigned to metaboilsm crates for a 35-day post-weaning nitrogen and energy balance experiment.

Effect of Dietary Protein and Food Restriction on Milk Production and Composition, Maternal Tissues and Enzymes in Lactating Rats

Lactating rats have been fed either a protein-restricted diet (10 vs. 20% casein in the control diet) or the control diet at 80, 60 and 40% of the voluntary intake for 7 d from d 7 of lactation. Food consumption, changes in maternal live weight, litter live weight gain and the mass of several maternal tissues were determined together with the activity of several mammary and liver enzymes, including 10 that are essential for fatty acid and complex lipid synthesis. Milk production was estimated from the litter weight gain and litter weight. Lactating rats fed the 20% protein diet ad libitum consumed three times that of nonlactating rats; their liver and kidney masses were significantly higher and their adipose mass was lower. The livers of the lactating rats were fatty, containing 118 mg lipid/g compared with 42 mg/g for the nonlactating rats. Lactating rats fed either the protein-restricted diet or the control diet at 40 and 60% of the ad libitum intake of the control diet had lower mammary, liver and iddney masses than rats consuming the control diet ad libitum. Both protein and food restriction led to lower rates of milk production than those of ad libitum—fed control rats as evidenced by the decrease in litter live weight gains. The concentrations of total lipid, total protein and lactose in milk were not affected by these dietary treatments. The concentration of α-lactalbumin in milk of rats fed the low protein diet was, however, lower than that in the milk of all rats receiving the control diet, irrespective of intake. Consumption of the restricted diets resulted in only small changes in specific activities (u/mg protein) of 15 mammary enzymes. In the livers, lactation led to higher specific activities of all four soluble lipogenic enzymes examined but did not affect the particulate enzymes involved in complex lipid synthesis. The dietary restrictions resulted in lower specific activities of the soluble enzymes compared with those of the lactating rats consuming the control diet ad libitum without affecting the particulate enzymes. Total activities of these enzymes were, however, lower than those for the control rats as a result of the smaller liver mass in the rats receiving the restricted diets.

Hypertension, Maternal Weight Gain and Birthheight

Data was collected from the obstetric records of 1371 primigravidae, a total series between 1976 and 1977 for Aberdeen City District. Only cases with complete information were analysed (947). The influence of maternal stature upon standardised birthweight has been confirmed, but this is different for those with proteinuric pre-eclampsia. Change in maternal weight over the pregnancy has an effect on birthweight as expected. Of the blood pressure variables studied, diastolic blood pressure at week 20 has a significantly negative effect on birthweight where all cases are taken together, but the major effect appears with cases of proteinuric pre-eclampsia where the change in diastolic blood pressure over pregnancy has a substantial effect on birthweight. The problem of analysis using both the change in weight and blood pressure over different intervals of pregnancy in predicting either pre-eclampsia or birthweight are discussed.

Birth to weaning in 4 days: remarkable growth in the hooded seal, Cystophora cristata

A brief lactation period with rapid neonatal weight gain may be adaptive for seals breeding on unstable pack ice. We studied the duration of lactation and growth of known-age pups of the hooded seal, Cystophora cristata, on the pack ice off Labrador. Mean body weight of pups increased from 22.0 kg at birth (n = 21) to a maximum of 42.6 kg on day 4 (n = 11) and then declined. On the basis of maternal absence, weight change, gastric contents, and clarity of blood serum, we conclude that pups are weaned 4 days after birth (range, 3–5 days). This is the shortest lactation period known for any mammal. Tagged pups captured on sequential days gained on average 7.1 kg per 24 h from the day after birth to weaning. Maternal effort supported a relative rate of weight gain (145 g∙kg maternal weight−0.75∙day−1) that is 2.5–6 times that of other phocids. By combining a large birth weight with rapid neonatal weight gain, hooded seals achieve a weaning weight comparable to other phocids in one-third to one-tenth the amount of time after birth.

Carbamazepine protein binding and disposition in pregnancy.

The pregnancies of five women with epilepsy treated with carbamazepine monotherapy were studied prospectively. Free and total serum concentrations of carbamazepine and its epoxide and dihydrodiol metabolites were analyzed at monthly intervals from the first trimester through 8 weeks postpartum. Assays were by high performance liquid chromatography, and free compounds were separated by ultrafiltration. The mean intrinsic clearance of carbamazepine (clearance of free drug corrected for changes in maternal body weight) did not change appreciably during pregnancy and the postpartum period. The mean free fractions of carbamazepine and the epoxide were elevated during pregnancy (0.25 and 0.50) compared with postpartum (0.22 and 0.43). Mean total maternal carbamazepine and epoxide concentrations were 40 and 48% higher than neonatal levels at birth, but maternal and neonatal free concentrations agreed closely. The ratio of epoxide to parent drug increased during pregnancy, as reported by other authors. Evidence is presented that this may be a result of inhibition of further biotransformation of the epoxide rather than of increased production. Two patients missed at least one dose of carbamazepine during labor, resulting in markedly reduced serum concentrations at delivery.

Outcome of maternal nutritional supplementation: a comprehensive review of the Bacon Chow study

In a double blind controlled intervention, two groups of nutritionally at-risk rural Taiwanese women were given a nutrient-rich dietary supplement (group A, n = 114) or a placebo (group B, n = 111) beginning after the birth of one child and continuing through the lactation period for a subsequent child. Outcome variables assessed include infant birth measurements postnatal physical growth, motor, mental, and dental development, morbidity, and maternal weight and skinfold changes during pregnancy and lactation. While few A-B differences in mean values of outcome variables were found, there were significant responses in subgroups of the sample. Comparisons of infants born after a nutrient-supplemented pregnancy (A2) versus an unsupplemented pregnancy (A1) showed that A2 male infants weighed more than A1 males at birth, and A1-A2 sibling correlations in birth measurements, especially Rohrer's index (wt/l3) were significantly reduced. Important mediators of supplement effects included sex of the offspring, season of birth, maternal body size, and birth of a previous infant characterized by dysmorphic prenatal growth. The limited effects of supplementation on the population as a whole may reflect the operation of long term adaptations which allow women to maintain reproductive success despite their apparent marginal nutritional status.

Raw soybeans for gestating swine.

An experiment was conducted to determine the influence of feeding ground raw soybeans to swine during gestation on reproductive performance for three consecutive parities. Sixty crossbred gilts were bred and randomly assigned to two dietary treatments with 30 gilts/treatment. The diets were formulated to contain 14% crude protein with either soybean meal (SBM) or raw soybeans (RSB) serving as the source of supplemental protein. All animals were fed in individual gestation stalls and were given 1.81 kg of feed/d. Upon entering the farrowing house at approximately 110 d of gestation, all animals, regardless of previous treatment, were fed the same lactation diet (15% protein corn-soybean meal diet) until the pigs were weaned (28 d). After completing three parities, 88 of a possible 90 litters were farrowed by each dietary group. Total number of live pigs at parturition and 21 d for three parities were: (SBM) 887, 732 and (RSB) 924, 765, respectively. Average pig birth and 21-d weights for each dietary group were (SBM) 1.52, 5.42 and (RSB) 1.59, 5.41 kg, respectively. Pigs from dams fed RSB had higher average pig birth weights (P less than .05), but weaning weights were not affected. There were no significant differences in maternal weight changes during gestation. Milk samples were collected within 6 h after parturition, 3 and 14 d of lactation. Percentage milk fat for each time period was: (SBM) 5.6, 9.0, 7.0 and (RSB) 6.3, 10.7, 6.5, respectively. Sows fed RSB had a higher milk fat at 3 d (P less than .05) but a lower milk fat at 14 d (P less than .1) than did the sows fed SBM. The study indicated RSB can be effectively utilized in gestation diets fed to swine.

Teratogenic dose-response relationships of etretinate in the golden hamster

Etretinate (Ro 10-9359; Tigason; 4-methoxy-2,3,6-trimethylphenyl analog of retinoic acid, ethyl ester) was evaluated for teratogenic activity in the Syrian golden hamster, Groups of pregnant hamsters were given a single oral dose of 2.8–88 mg/kg etretinate during the early primitive streak stage of gestation. No signs of maternal intoxication were observed in any of the hamsters given the retinoid and maternal body weight changes throughout gestation were not significantly different from those of the vehicle-treated group. Etretinate administration was associated with a dose-dependent increase in the incidence and severity of malformations. The average fetal body weight was significantly less in litters recovered from dams given 44 or 88 mg/kg of etretinate when compared to the average body weight of fetuses recovered from dams given an equivalent volume of the vehicle. The average crown-rump lengths also were significantly shorter in fetuses taken from the dams given 44 or 88 mg/kg etretinate as compared to the control group. The malformations induced by etretinate administration were similar to those noted following an oral dose of all- trans-retinoic acid ( Willhite and Shealy, 1984). A comparison of the dose-response curves for induction of terata following treatment with etretinate or all- trans-retinoic acid revealed that etretinate was twice as potent as a teratogen in the hamster as all- trans-retinoic acid. Teratogenic activity of etretinate in the hamster was achieved at doses (mg/kg body wt) used in patients at current clinical therapeutic levels.

The partition of body-weight gain in the pregnant sow

1. 1. The body-weight gain of pregnant gilts was partitioned into reproductive (gravid uterus and mammary tissue) and net maternal components and was compared at feeding levels of 1.8 and 2.5 kg/day (20 and 30 MJ metabolizable energy (ME), respectively), at three specific stages of gestation; 40–60 days (early), 60–80 days (mid) and 90–110 days (late). Non-pregnant litter sisters were provided for comparison. 2. 2. The increase in body weight of the animals was directly related to the level of feed intake and was significantly higher for the pregnant animals. 3. 3. Reproductive gain increased during pregnancy and was only dependent upon feeding level in late gestation. The net maternal gain and the differences between pregnant and non-pregnant animals varied with both feeding level and stage of gestation. Calculation of the rates of gain revealed that it was only in late gestation that the net maternal gain of the pregnant animals at the high feed intake was lower than that of the non-pregnant animals. At the low feed intake, on the other hand, there was a progressive decrease in the maternal tissue deposition of the pregnant animals with stage of gestation, and with the exception of the values in early pregnancy, they were always lower than those of their non-pregnant sisters. 4. 4. The implications of the changes in maternal body weight on the long-term reproductive performance and metabolic status of the sow are discussed.

Effects of Maternal Drinking and Marijuana Use on Fetal Growth and Development

A study of 1,690 mother/child pairs at Boston City Hospital was conducted to assess the impact of maternal alcohol consumption on fetal development when confounding variables were controlled. Level of maternal drinking prior to pregnancy was associated with shorter duration of gestation. Lower maternal weight change, history of maternal illnesses, cigarette smoking, and marijuana use, however, were more consistently related to adverse fetal growth and development. New findings in this study include a negative association between maternal marijuana use during pregnancy and fetal growth. Also when confounding variables were controlled, women who used marijuana during pregnancy were five times more likely to deliver infants with features considered compatible with the fetal alcohol syndrome.

Effects of Maternal Drinking and Marijuana Use on Fetal Growth and Development

A study of 1,690 mother/child pairs at Boston City Hospital was conducted to assess the impact of maternal alcohol consumption on fetal development when confounding variables were controlled. Level of maternal drinking prior to pregnancy was associated with shorter duration of gestation. Lower maternal weight change, history of maternal illnesses, cigarette smoking, and marijuana use, however, were more consistently related to adverse fetal growth and development. New findings in this study include a negative association between maternal marijuana use during pregnancy and fetal growth. Also when confounding variables were controlled, women who used marijuana during pregnancy were five times more likely to deliver infants with features considered compatible with the fetal alcohol syndrome.

Pregnancy and lactation in the obese rat: Effects on maternal and pup weights

Lister hooded female rats, fed palatable high energy foods and chow, weighed significantly more than chow-fed control rats before mating. A smaller proportion of the obese rats became pregnant, and they lost more litters in lactation. When litters survived (7±1 pups), maternal weight changes differed between groups during lactation. The controls gained 6.2±3.2 g, whereas the obese rats lost variable amounts of weight despite the continued availability of the palatable diet. The rats that were heaviest at mating and parturition and which showed the largest non-fetal weight gains in pregnancy (i.e., the “large weight loss group”) lost 60.6±4.8 g, while less obese rats which showed similar non-fetal gains to controls (i.e., the “small weight loss group”) lost 24.6±3.2 g. Thus the weights of all groups converged and were similar after three weeks of lactation, but diverged again after weaning. During lactation the total energy intakes and amounts of protein consumed by the obese rats were significantly below those of controls, and total fat intake was significantly elevated. Although litter size and pup weights did not differ significantly at birth, pups of obese mothers weighed significantly less than those of controls at weaning. Maternal obesity in lactation appears to influence both body weight regulation and lactational performance.

The effect of weight at mating and of nutrition during mid-pregnancy on the birth weight of lambs from primiparous ewes

SUMMARYForty-eight approximately 18-month-old Scottish Blackface ewes were used to study the effects of two levels of nutrition during mid-pregnancy (30–98 days of gestation) on the birth weight of lambs from ewes varying in weight, size and condition at first mating. The mean live weight (42–4 kg), size index (31–9) and condition score (2–4) at mating of the 26 ewes from flock A were all less than those of the 22 ewes from flock B (54–5, 39–4 and 2–9 respectively). Mean intakes of the low and high nutritional treatment ewes during mid-pregnancy were 10–6 and 22–0 g/kg/day respectively of a pelleted diet supplying 8–81 MJ metabolizable energy and 125–5 g crude protein/kg. These intakes produced estimated changes in net maternal weight of approximately – 5 and 0 kg respectively.Mean lamb birth weights from ewes on the low and high nutritional treatments were:flock A, 3–32 and 3–83 kg; flock B, 4–96 and 4–23 kg respectively. Analyses showed intake during mid-pregnancy to have a positive effect on lamb birth weight in the flock A ewes, and a negative effect in flock B ewes. Mating weight accounted for 78% of the variance in birth weight in the low nutritional treatment ewes but had little effect in those on the higher level of feeding.The practical implications of the results are discussed in relation to levels of juvenile nutrition.

The effect of dietary protein concentration and quality on the hormonal status, protein metabolism and milk protein concentrations of rats.

Lactating rats were fed casein or cereal protein at one of two concentrations. Milk volume was severely reduced by poor dietary protein quality. Milk fat, lactose and free amino acid nitrogen were unaffected by the diets, whereas total milk protein was reduced by 20% on the cereal diets. Lactalbumin concentrations showed a greater decrease than that of other milk proteins. Changes in maternal serum insulin, corticosterone, albumin and body weight suggest maternal metabolism changes to provide substrate for milk synthesis. Total milk protein and serum albumin synthesis show similar sensitivity to dietary protein adequacy.

Studies on reproduction in prolific ewes. 4. Sequential changes in the maternal body during pregnancy

SUMMARYSeventy-eight Finnish Landrace × Dorset Horn ewes in lamb to Suffolk rams were slaughtered serially between 50 and 145 days of gestation. The mean litter size was 2·7. The daily feeding regime aimed to provide each ewe with 15 MJ of metabolizable energy (ME) in the first month of gestation and 9·4 MJ in the second and third. Thereafter the ewes were provided with a basal intake of either 9·6 MJ (low plane, LP) or 13·4 MJ (high plane, HP) plus 1·3 MJ for each foetus.For ewes with 2, 3 and 4 foetuses the mean percentage changes in maternal body weight over pregnancy were respectively — 5, — 10 and — 14 (LP) or + 3, — 2 and — 6 (HP). Changes in weights of blood, liver and the empty gastro-intestinal tract through gestation varied with the plane of nutrition but not with number of foetuses. In contrast, udder weight at parturition was dependent on number of foetuses but not on plane of nutrition.Increased hydration of the maternal tissues in late pregnancy tended to mask concurrent losses of body fat. For example, over the last 2 months, HP ewes carrying quadruplets lost on average 1·0 kg in body weight but 5·5 kg of (chemically determined) fat. The latter was lost at a rate which increased up to an average of 170 g/day over the last 2 weeks of pregnancy. Net changes in body protein were estimated to be relatively small, but there was some redistribution, including loss from muscle and gain by the udder. There was no evidence of any demineralization of the maternal skeleton.The practical significance of the changes in body composition is discussed, in particular that of the increasing rates of loss of body fat with increasing litter size. It is suggested that the dangers implicit in these rates of fat loss must be taken into consideration when deciding on dietary regimes and the timing of breeding cycles for highly prolific ewes, or indeed when embarking on a programme of increased prolificacy.