Increase In Mean Birth Weight Research Articles

Modifying effect of maternal nutritional status on the impact of maternal multiple micronutrient supplementation on birthweight in Indonesia

Low birthweight (LBW) and intrauterine growth restriction are linked with maternal nutritional status during pregnancy, and maternal supplementation with multiple micronutrients (MMNs) is reported to increase birthweight. Responses to MMN, however, might be modified by maternal nutrition. To examine the differential effects of maternal nutritional status on birthweight responses to prenatal MMN supplementation, data from the Supplementation with Multiple Micronutrient Intervention Trial, a cluster-randomized trial in Indonesia was analyzed. Birthweight outcomes of 7001 infants whose mothers received iron/folic acid were compared with 7292 infants whose mothers received MMN. The modifying effects of maternal short-term nutritional status (mid-upper arm circumference (MUAC) and long-term nutritional status (height) on the birthweight response to MMN supplementation were assessed. For women with higher MUAC (≥23.5 cm), MMN increased mean birthweight by 33 g (95% confidence interval (CI): -1 to 66, P=0.06) and significantly reduced LBW by 21% (relative risk: 0.79, 95% CI: 0.64-0.99, P=0.04). The modifying effect of MUAC on mean birthweight, LBW and small for gestational age was significant. There was no evidence of a modifying effect of maternal height on the response to MMN. Supplementation with MMN in pregnancy increased birthweight, but maternal nutritional status modified this response, with infants born to women with better short-term nutrition having greater birthweight response.

Low birth weight persists in South Asian babies born in England and Wales regardless of maternal country of birth. Slow pace of acculturation, physiological constraint or both? Analysis of routine data

BackgroundThe mean birth weight of offspring of Bangladeshi, Indian and Pakistani women tends to be among the lowest of any ethnic groups regardless of country of residence. However, it is...

453 Limited Significance of Weight Gain During Pregnancy on Birth Weight

Background and aim: Data from The Medical Birth Registry of Norway show a temporary increase in mean birth weight and proportion of large babies in parallel with changes in national consumption of sugar-containing beverages. The aim was to study to what extent weight increase during pregnancy, which may reflect consumption of carbohydrates, affects birth weight. Methods: During 2001-2009 15054 live term (37- 42 weeks) singleton pregnancies were registered in the Oppland county pregnancy database. Time trends were examined, and 9282 births with complete information were subjected to multiple linear regression analysis. Birth weight (BW) was related to age, height, pre-pregnancy BMI (ppBMI), chronic diseases, parity, pregnancy complications, smoking and gestational weight gain (GWG) in the mother, and gestational age (GA), sex, and registered malformations in the child. Results: During the study period mean BW decreased from 3658 to 3574 gram (p< 001). Mean ppBMI increased from 24.25 to 24.78, GWG decreased from 15.15 to 13.93 kg, smokers decreased from 22.7 to 11.5%, GA decreased from 39.79 to 39.50 weeks, (p< 001 for all). Our model explained 33% of the variability in BW. BW increased 18.9 (95%CI; 17.4,20.4) g per kg GWG, 21.7 (19.9,23.5) g per unit ppBMI, 13.1 (11.7,14.4) g per 1 cm mother's height, 141.8 (135.0-148.6) g per week GA, and 105.7 (89.3-122.2) g for male sex, and decreased 187.3 (164.6, 210.1) g for smoking and 182.7 (164.5,200.9) g for being primipara. Conclusion: Pregnancy weight gain and prepregnancy BMI have significant, but limited, impact on birth weight.

Multiple Micronutrient Supplementation during Pregnancy in Developing-Country Settings: Policy and Program Implications of the Results of a Meta-Analysis

An independent Systematic Review Team performed a meta-analysis of 12 randomized, controlled trials comparing multiple micronutrients with daily iron-folic acid supplementation during pregnancy. To provide an independent interpretation of the policy and program implications of the results of the meta-analysis. A group of policy and program experts performed an independent review of the meta-analysis results, analyzing internal and external validity and drawing conclusions on the program implications. Although iron content was often lower in the multiple micronutrient supplement than in the iron-folic acid supplement, both supplements were equally effective in tackling anemia. Community-based supplementation ensured high adherence, but some mothers still remained anemic, indicating the need to concomitantly treat infections. The small, significant increase in mean birthweight among infants of mothers receiving multiple micronutrients compared with infants of mothers receiving iron-folic acid is of similar magnitude to that produced by food supplementation during pregnancy. Larger micronutrient doses seem to produce greater impact. Meaningful improvements have also been observed in height and cognitive development of the children by 2 years of age. There were no significant differences in the rates of stillbirth, early neonatal death, or neonatal death between the supplemented groups. The nonsignificant trend toward increased early neonatal mortality observed in the groups receiving multiple micronutrients may be related to differences across trials in the rate of adolescent pregnancies, continuing iron deficiency, and/or adequacy of postpartum health care and merits further investigation. Replacing iron-folic acid supplements with multiple micronutrient supplements in the package of health and nutrition interventions delivered to mothers during pregnancy will improve the impact of supplementation on birthweight and on child growth and development.

Possible association of folic acid supplementation during pregnancy with reduction of preterm birth: a population-based study

Objective Periconceptional folic acid or multivitamin supplementation is recommended for prospective pregnant women to prevent neural-tube defects. The question is whether it is worth continuing these supplementations after the first trimester of pregnancy or not. Thus the possible fetal growth promoting and/or preterm birth reducing effect of vitamin supplements in the second and mainly in the third trimester was studied. Study design Comparison of birth outcomes of singletons born to primiparous pregnant women with prospectively and medically recorded vitamin supplement in the population-based data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities (HCCSCA), 1980–1996 contained 6293, 169, and 311 primiparae with folic acid alone, multivitamins and folic acid + multivitamin supplementation, respectively, and their data were compared to the data of 7319 pregnant women without folic acid and folic acid-containing multivitamin supplementation as reference. Results Mean gestational age was 0.3 week longer and mean birth weight was by 37 g higher in the group of folic acid alone, than in the reference group (39.2 weeks; 3216 g). The rate of preterm births (7.6%) was significantly lower compared with the reference sample (11.8%), but the rate of low birth weight newborns did not show significant reduction. Folic acid alone in the third trimester associated with 0.6 week longer gestational age and a more significant reduction in the rate of preterm births (4.8%). Conclusions Minor increase in mean birth weight after high dose of folic acid supplementation during pregnancy would not be expected to result in too large babies; however, the significant reduction in the rate of preterm births may have great public health benefit.

Interventions for promoting smoking cessation during pregnancy.

Tobacco smoking in pregnancy remains one of the few preventable factors associated with complications in pregnancy, low birthweight, preterm birth and has serious long-term health implications for women and babies. Smoking in pregnancy is decreasing in high-income countries and increasing in low- to middle-income countries and is strongly associated with poverty, low educational attainment, poor social support and psychological illness. To assess the effects of smoking cessation interventions during pregnancy on smoking behaviour and perinatal health outcomes. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2008), the Cochrane Tobacco Addiction Group's Trials Register (June 2008), EMBASE, PsycLIT, and CINAHL (all from January 2003 to June 2008). We contacted trial authors to locate additional unpublished data. Randomised controlled trials where smoking cessation during pregnancy was a primary aim of the intervention. Trials were identified and data extracted by one person and checked by a second. Subgroup analysis was conducted to assess the effect of risk of trial bias, intensity of the intervention and main intervention strategy used. Seventy-two trials are included. Fifty-six randomised controlled trials (over 20,000 pregnant women) and nine cluster-randomised trials (over 5000 pregnant women) provided data on smoking cessation outcomes.There was a significant reduction in smoking in late pregnancy following interventions (risk ratio (RR) 0.94, 95% confidence interval (CI) 0.93 to 0.96), an absolute difference of six in 100 women who stopped smoking during pregnancy. However, there is significant heterogeneity in the combined data (I(2) > 60%). In the trials with the lowest risk of bias, the interventions had less effect (RR 0.97, 95% CI 0.94 to 0.99), and lower heterogeneity (I(2) = 36%). Eight trials of smoking relapse prevention (over 1000 women) showed no statistically significant reduction in relapse.Smoking cessation interventions reduced low birthweight (RR 0.83, 95% CI 0.73 to 0.95) and preterm birth (RR 0.86, 95% CI 0.74 to 0.98), and there was a 53.91g (95% CI 10.44 g to 95.38 g) increase in mean birthweight. There were no statistically significant differences in neonatal intensive care unit admissions, very low birthweight, stillbirths, perinatal or neonatal mortality but these analyses had very limited power. Smoking cessation interventions in pregnancy reduce the proportion of women who continue to smoke in late pregnancy, and reduce low birthweight and preterm birth. Smoking cessation interventions in pregnancy need to be implemented in all maternity care settings. Given the difficulty many pregnant women addicted to tobacco have quitting during pregnancy, population-based measures to reduce smoking and social inequalities should be supported.

Effects of a dairy product fortified with multiple micronutrients and omega-3 fatty acids on birth weight and gestation duration in pregnant Chilean women

To test the hypothesis that maternal food fortification with omega-3 fatty acids and multiple micronutrients increases birth weight and gestation duration, as primary outcomes. Non-blinded, randomised controlled study. Pregnant women received powdered milk during their health check-ups at 19 antenatal clinics and delivered at two maternity hospitals in Santiago, Chile. Pregnant women were assigned to receive regular powdered milk (n = 477) or a milk product fortified with multiple micronutrients and omega-3 fatty acids (n = 495). Intention-to-treat analysis showed that mean birth weight was higher in the intervention group than in controls (65.4 g difference, 95% confidence interval (CI) 5-126 g; P = 0.03) and the incidence of very preterm birth (0.80 just for mean birth weight and birth length in the on-treatment analysis; birth length in that analysis had a difference of 0.57 cm (95% CI 0.19-0.96 cm; P = 0.003). The new intervention resulted in increased mean birth weight. Associations with gestation duration and most secondary outcomes need a larger sample size for confirmation.

Trends in birthweight in the north of England

This article describes trends in population birthweight distribution in the north of England between 1982 and 2000, and reviews the international literature on recent birthweight trends in industrialized populations. Two contrasting trends were observed: an increase in low birthweight from 7.0% to 7.7% of all births, and an increase in births weighing 3500 g or more, consistent with an increase in mean birthweight. The rate of multiple births increased over the study period, and multiple births accounted for about half of the increase in low birthweight. Multiple births are rising due to increasing maternal age, and the development and use of assisted reproductive technologies. Low birthweight increased in both multiple and singleton births, due entirely to increased low-birthweight live births. There was a substantial reduction in low-birthweight stillbirths. The rise in low-birthweight live births is multifactorial, but changes in registration practice and increased elective delivery are likely contributory factors. The increase in high birthweights is likely to reflect reductions in smoking during pregnancy, and increased maternal height and weight. The dramatic recent rise in maternal body mass index (BMI) at booking is likely to have a substantial impact on birthweight and adverse perinatal outcomes in coming decades.

Insecticide-Treated Nets for the Prevention of Malaria in Pregnancy: A Systematic Review of Randomised Controlled Trials

BackgroundProtection from malaria with insecticide-treated bednets (ITNs) during pregnancy is widely advocated, but evidence of benefit has been inconsistent. We undertook a systematic review of randomised trials.Methods and FindingsThree cluster-randomised and two individually randomised trials met the inclusion criteria; four from Africa (n = 6,418) and one from Thailand (n = 223). In Africa, ITNs compared to no nets increased mean birth weight by 55 g (95% confidence interval [CI] 21–88), reduced low birth weight by 23% (relative risk [RR] 0.77, 95% CI 0.61–0.98), and reduced miscarriages/stillbirths by 33% (RR 0.67, 0.47–0.97) in the first few pregnancies. Placental parasitaemia was reduced by 23% in all gravidae (RR 0.77, 0.66–0.90). The effects were apparent in the cluster-randomised trials and the one individually randomised trial in Africa. The trial in Thailand, which randomised individuals to ITNs or untreated nets, showed reductions in anaemia and fetal loss in all gravidae, but not reductions in clinical malaria or low birth weight.ConclusionsITNs used throughout pregnancy or from mid-pregnancy onwards have a beneficial impact on pregnancy outcome in malaria-endemic Africa in the first few pregnancies. The potential impact of ITNs in pregnant women and their newborns in malaria regions outside Africa requires further research.

Can we explain why Brazilian babies are becoming lighter?

We tried to explain why a marked decrease in birthweight of 122 g occurred over a 15-year period in Ribeirão Preto, Brazil. Factors reflecting biological, social, and health care characteristics (infant gender, parity, maternal age, marital status, type of hospital, maternal smoking, preterm birth, small for gestational age [SGA], and prenatal care) were assessed on 6711 newborns in 1978/1979 and 2838 in 1994 using multiple linear regressions. The birthweight distribution shifted to the left and the residual distribution of small preterm babies increased from 1.9% to 3.4%. Only marital status and preterm delivery would have decreased the difference in birthweight over time, explaining for each of them around 30 g of the 122 g. Increasing levels of attendance at antenatal care over time might have decreased the birthweight difference by 40 g. Maternal age and SGA explained little of the decreasing trend. Reductions in maternal smoking would have increased mean birthweight slightly. In stratified analysis the downward trend was more marked among mothers with high education (-202 g) and those delivered by caesarean section (-194 g). After adjusting for all those significant variables mean birthweight was still 74 g (95% CI: -97, -50 g) lower in 1994 than in 1978/1979. The trend could be explained in part by factors related to marital status that might reflect dysfunctional families in the Brazilian context and the preterm increase that might be associated with advances in medical technology. The high attendance at antenatal clinics or factors associated with it might have prevented a further decrease in birthweight. Our results may be compatible with the high economic development of Ribeirão Preto within Brazil, together with factors associated with its unfavourable lifestyle.

Malaria prevention strategies.

Acute and severe consequences of pregnancy-associated malaria (PAM), such as materno-fetal death or cerebral malaria, seem limited to unstable malaria areas. In areas of stable endemicity, the main consequences are maternal anaemia and low birth weight (LBW) babies, particularly in primigravidae. Placental malaria seems more frequent and its consequences more severe in HIV-infected women. Since 1964, several chemoprophylaxis controlled trials have been undertaken, mainly in Tropical Africa where malaria is stable. Most showed an increase in mean birth weight in the prophylaxis group, especially among primigravidae. Similar findings were made with anaemia. Prophylaxis seems less effective in the case of HIV-malaria co-infection, which may require an increase in the number of doses. At present, intermittent treatment with sulfadoxine-pyrimethamine given twice or thrice during pregnancy in antenatal clinics seems the best policy for preventing PAM. Such effective prophylaxis should be integrated with other antenatal clinic services. Recently identified molecular receptors involved in cytoadherence of parasitized erythrocytes to placenta could yield new therapeutic or vaccine approaches, specifically targeted to pregnant women.

Effects of psychosocial risk factors and prenatal interventions on birth weight: evidence from New Jersey's HealthStart program.

Many states developed and implemented multifaceted Medicaid prenatal care programs in the late 1980s in response to expansions in Medicaid eligibility. Although these new programs were based on the presumed relationships between psychosocial risk factors, early prenatal care, prenatal interventions and birth outcomes, research has not verified all of these linkages. Data were collected on 90,117 women who took part in New Jersey's comprehensive prenatal care program, HealthStart, between 1988 and 1996. The impact of psychosocial risk factors and prenatal interventions on mean birth weight and the odds of low birth weight (less than 2,500 g) was assessed using ordinary least-squares regression and logistic regression, respectively. After controls were introduced for social and demographic, psychosocial and behavioral factors, as well as the woman's county of residence and the year of her baby's birth, smoking, drinking and using hard drugs (but not marijuana) during pregnancy were independently associated with reductions in mean birth weight (of 123g, 29g and 137g, respectively) and with increases in the odds of low birth weight (odds ratios, 1.4, 1.2 and 1.7, respectively). However, according to the fully adjusted model, which also controlled for medical risk factors and prenatal services, the interventions designed to reduce those behaviors had no favorable effects on birth weight. In contrast, the receipt of services in the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) was associated with an increase in mean birth weight of 22g (and of 48g among inadequately nourished women only), and with a reduction in the risk of low birth weight (odds ratio, 0.87). Referrals to WIC services should be a key feature of prenatal care programs for poor women.

Effects of alternative maternal micronutrient supplements on low birth weight in rural Nepal: double blind randomised community trial

Objective: To assess the impact on birth size and risk of low birth weight of alternative combinations of micronutrients given to pregnant women.Design: Double blind cluster randomised controlled trial.Setting: Rural...

The potential benefits of using fish oil in relation to preterm labor: the case for a randomized controlled trial?

The potential benefits of using fish oil in relation to preterm labor: the case for a randomized controlled trial?

A double-blind randomised controlled trial of continuous oxygen therapy for compromised fetuses

Objective To investigate the effect of chronic oxygen therapy in fetuses with absent end diastolic flow in the umbilical artery assessed by doppler analysis at 24–30 weeks of gestation. Design A double-blind, randomised control trial was performed with patients blindly allocated to receive humidified oxygen or humidified air. Setting A tertiary referral hospital in South Africa. Participants Thirty-two women who presented between 24 and 30 weeks of gestation with a confirmed finding of absent end diastolic flow in the umbilical artery. Methods After randomisation patients were allocated to receive a 40% mixture of humidified oxygen or humidified air from uniform coloured gas cylinders which were marked either ‘a’ or ‘b’ All women received betamethasone from 27 weeks of gestation on a weekly basis. Cardiotocographs were used from 28 weeks of gestation; after 28 weeks of gestation an amniocentesis was considered to confirm fetal maturity. Women were expected to breath the allocated gas continuously apart from meals and visits to the toilet. Main outcome measures Survival of the fetus was the main outcome measure with secondary outcome measures documenting improvement in the fetal condition in utero. Results There were 16 women randomised to receive oxygen and 16 to receive air. There were nine survivors in the oxygen group (56.3%) and six in the air group (37.5%) (relative risk 1.5, 95% confidence interval 0.7–3.2). There was a nonsignificant increase in mean birthweight in the oxygen group (858.3 grammes vs 774.4 grammes) and a nonsignificant increase in mean duration of treatment in the oxygen group (12.8 days vs 10.4 days). Conclusion This study did not demonstrate that chronic oxygen therapy provides any benefits to compromised fetuses between 24 and 30 weeks of gestation. Larger studies with sufficient power are necessary to assess whether oxygen therapy can reduce perinatal mortality by a clinically useful amount in this group of patients.

Birthweight distribution at Korle-Bu Teaching Hospital, Ghana.

To determine the birthweight distribution of singleton births at the Korle-Bu Teaching Hospital and to determine if selected socio-demographic and reproductive characteristics that are known to be associated with birthweight would show the association in our setting. A non-randomised cross-sectional survey of all deliveries within the study period. Korle-Bu Teaching Hospital, a tertiary institution, delivering about 11,000 women a year. From 1st November to 12th December 1994, 866 singleton normally formed livebirths and fresh stillbirths were sequentially enrolled. Data sources were the antenatal and delivery records of the subjects and an interviewer-administered questionnaire. The mean birthweight for the total sample was 3070 g +/- 616 g. One hundred and fifteen (13.3%) babies were low birthweight. The mean birthweight for those with reliable dates and born at term was 3262 g +/- 488.8 g. Multiple logistic regression analysis showed lack of antenatal malaria chemoprophylaxis and a history of previous low birthweight to be significantly associated with low birthweight. Although the mean birthweight of Korle-Bu babies was lower than those of USA and UK babies, it was comparable with those from other developing countries. Antenatal malaria chemoprophylaxis is a practical intervention that can produce an increase in mean birthweight and reduce the risk of low birthweight in our population.

Secular trend in birthweight among the Purari delta population, Papua New Guinea

The aim of this analysis was to examine the extent and possible seasonal nature of the secular trend in mean birthweight in the Purari delta, Papua New Guinea. This is a country undergoing rapid modernization, and with this has come a secular trend toward increased adult body size in some parts of the country but not others. Birthweight data, collected by month of delivery at Kapuna Hospital in the Purari delta between the years 1969 and 1996, was analysed by year of birth and by season, using one-way analysis of variance and post hoc Scheffé tests with the statistical software SPSS-PC+. A total of 927 birthweights for the years 1969, 1972, 1977, 1994 and 1996 were included in the analysis. Twin births were excluded from analysis, as were births below 1.5 kg. There is clear evidence of a secular trend in increasing mean birthweight between the period 1969 and 1996, with the largest significant difference being between 1977 and 1994, from 2.70 to 2.92 kg. There were no significant differences in mean birthweight between the sexes. The rate of birthweight increase between 1977 and 1994 was 130 g per decade, lower than the gain of 200 g per decade in the period 1994-1996. The decline in birthweight of 90 g per decade during the period 1969-1977 is not statistically significant. The proportion of infants born with low birth weight (< 2.5 kg) shows an increase between 1969 and 1972, and a decline thereafter. While seasonal differences in birthweight during any of the years examined is non-significant, significantly greater mean birthweight across the period 1969-1996 was found for births during the wet season (April to July), and the drier season (August to November), respectively. The secular increase in mean birthweight is likely to be a consequence of the improvements in maternal diet and increased maternal body size that have come with economic modernization. The secular trend of seasonality in mean birthweight among the Purari delta population may be a function of seasonally varied displacement of traditional diet by non-local bought foods, as well as reduced seasonality of maternal workload associated with the processing of the traditional staple food.

Chloroquine prophylaxis, iron-folie acid supplementation or case management of malaria attacks in primigravidae in western Uganda: effects on maternal parasitaemia and haemoglobin levels and on birthweight

The effects of weekly chloroquine prophylaxis, daily iron-weekly folic acid supplementation or passive case management on maternal haemoglobin and parasitaemia and on birthweight were examined in primigravidae in a randomized, double-blind placebo-controlled intervention trial in 1996–1998 in Hoima District, western Uganda. Iron-folic acid supplementation significantly increased mean birthweight as compared to case management ( P = 0·03). Low birthweight (< 2·5 kg) occurred in 2% of babies of women receiving chloroquine prophylaxis for ≥ 8 weeks and in 9% in the case management group (RR = 0·36, 95% CI 0·13–1·00, P = 0·009). Parasitaemia at enrolment significantly correlated with low birthweight in the case management group as compared to the intervention groups ( P = 0·02). Women in the case management group who were parasitaemic and had haemoglobin levels < 100 g/L at delivery had babies with lower mean birthweight as compared to babies in the other groups ( P = 0·04). Low haemoglobin level at enrolment, irrespective of parasitaemia status, was a predictor of low birthweight in the case management group only ( P = 0·04). Chloroquine prophylaxis and iron-folic acid supplementation significantly increased maternal haemoglobin levels during pregnancy as compared to case management ( P = 0·01 and 0·007, respectively) and the increase correlated to the duration of the intervention.

Interventions for promoting smoking cessation during pregnancy.

Smoking remains one of the few potentially preventable factors associated with low birthweight, very preterm birth and perinatal death. The objective of this review was to assess the effects of smoking cessation programs implemented during pregnancy on the health of the fetus and infant, on the mother and on the family. We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Tobacco Addiction Group trials register. Randomised and quasi-randomised trials of smoking cessation programs implemented during pregnancy. Trial quality was assessed and data were extracted independently by two reviewers. Forty-four trials were identified: 37 trials including 16,916 women provided data on smoking cessation and/or perinatal outcomes, as did one cluster-randomised trial including 3000 women. Over 800 women were included in trials of smoking relapse prevention. There was substantial variation in the intensity of the intervention and the extent of reminders and reinforcement through pregnancy. Based on 34 trials there was a significant reduction in smoking in the intervention groups (odds ratio 0.53, 95% confidence interval 0. 47 to 0.60), an absolute difference of 6.4% women continuing to smoke. The eight trials with validated smoking cessation, a high intensity intervention and a high quality score had an odds ratio of 0.53, 95% confidence interval 0.44 to 0.63 and an absolute difference in continued smoking of 8.1%. The subset of trials with information on fetal outcome revealed a reduction in low birthweight (odds ratio 0.80, 95% confidence interval 0.67 to 0.95), a reduction in preterm birth (odds ratio 0.83, 95% confidence interval 0.69 to 0. 99) and an increase in mean birthweight of 28g (95% confidence interval 9 to 49). There were no differences in very low birthweight or perinatal mortality. Five trials of smoking relapse prevention showed no significant difference. The single large cluster-randomised trial showed no evidence of a decrease in continued smoking or adjusted mean birthweight. Smoking cessation programs in pregnancy appear to reduce smoking, low birthweight and preterm birth, but no effect was detected for very low birthweight or perinatal mortality.

Trends and social patterning of birthweight in Sheffield, 1985–94

AIMTo describe the trends in birthweight and their association with socioeconomic status in a 10 year birth cohort in Sheffield.METHODSData for all live singleton births were extracted from the Sheffield...