The effect of active and passive maternal smoking before and during pregnancy on neonatal weight at birth

The effect of active and passive smoking during pregnancy on birth outcomes: A cohort study in Shanghai

INTRODUCTION

China is the largest tobacco consumer in the world, and tobacco poses a serious threat to the health of pregnant women. However, there are relatively few domestic studies on smoking during pregnancy and childbirth outcomes among pregnant women. The purpose of this study was to analyze the effect of active and passive smoking on pregnant women and their pregnancy outcomes, providing evidence and recommendations for intervention measures.

METHODS

This was a cohort study in Shanghai from April 2021 to September 2023. According to the smoking status of pregnant women, they were divided into three groups: active smokers, passive smokers and non-smokers. A self-designed questionnaire was utilized to conduct the survey, and their pregnancy outcomes were tracked and followed up.

RESULTS

A total of 3446 pregnant women were included in this study, among which 2.1% were active smokers, 43.5% were passive smokers, and 54.4% were non-smokers. The average age of the pregnant women was 29.9 years, and 41.2% had a university degree or higher. The education level of active smokers and passive smokers was significantly lower than that of non-smokers (p<0.05).The average gestational age of non-smokers was 38.6 weeks, and the birth weight was 3283.2 g, which was higher than those of active smokers and passive smokers (p<0.05). Logistic regression analysis showed that passive smoking increased the likelihood of preterm birth (AOR=1.38; 95% CI: 1.05-1.81), low birth weight (AOR=1.53; 95% CI: 1.10-2.12), and intrauterine growth restriction (AOR=1.35; 95% CI: 1.02-1.79), while active smoking increased the likelihood of preterm birth (AOR=2.98; 95% CI: 1.50-5.90), low birth weight (AOR=4.29; 95% CI: 2.07-8.88), intrauterine growth restriction (AOR=2.70; 95% CI: 1.37-5.33) , and birth defects (AOR=2.66; 95% CI: 1.00-6.97).

CONCLUSIONS

Our findings illustrate that active and passive smoking can lead to adverse pregnancy outcomes. This study provides data on the relationship between smoking during pregnancy and delivery outcomes among pregnant women. In the future, we need more effective strategies to protect pregnant women from the harm of tobacco.

Excessive Gestational Weight Gain and Pregnancy Outcomes

Adequate weight gain during pregnancy is one of the factors for its proper course. Excessive weight gain during this period of a woman's life is associated with adverse pregnancy outcomes. In this study, we determine the impact of excessive gestational weight gain on pregnancy outcomes. The study is based on the results of a Polish national survey performed between 2011 and 2017 on a group of 10,319 women and 6930 children. Excessive weight gain during pregnancy was associated with higher birthweight and higher prevalence and risk of birthweight over 4500 g (OR 6.92; 95% CI 3.10-15.42), cesarean section/assisted delivery (OR 2.71; 95% CI 1.63-4.49), pregnancy induced hypertension (OR 5.85; 95% CI 3.24-10.57), hospitalization during pregnancy (OR 1.85; 95% CI 1.12-3.04), and the Apgar score in the first minute of neonate's life in the range of 0-7 (OR 2.65; 95% CI 1.36-5.2). We did not observe the significant difference in premature rupture of membranes and labor inductions. Our study indicates that excessive gestational weight gain is associated with higher risk for adverse pregnancy outcomes.

Maternal Iodine Status and Birth Outcomes: A Systematic Literature Review and Meta-Analysis

Background & aims: Iodine is important for thyroid function during pregnancy to support fetal growth, but studies of maternal iodine status and birth outcomes are conflicting. We aimed to quantify the association between iodine status and birth outcomes, including potential threshold effects using nonlinear dose−response curves. Methods: We systematically searched Medline and Embase to 10 October 2022 for relevant cohort studies. We conducted random-effects meta-analyses of urinary iodine concentration (UIC), iodine:creatinine ratio (I:Cr), and iodide intake for associations with birth weight, birth weight centile, small for gestational age (SGA), preterm delivery, and other birth outcomes. Study quality was assessed using the Newcastle-Ottawa scale. Results: Meta-analyses were conducted on 23 cohorts with 42269 participants. Birth weight was similar between UIC ≥ 150 μg/L and <150 μg/L (difference = 30 g, 95% CI −22 to 83, p = 0.3, n = 13, I2 = 89%) with no evidence of linear trend (4 g per 50 μg/L, −3 to 10, p = 0.2, n = 12, I2 = 80%). I:Cr was similar, but with nonlinear trend suggesting I:Cr up to 200 μg/g associated with increasing birthweight (p = 0.02, n = 5). Birthweight was 2.0 centiles (0.3 to 3.7, p = 0.02, n = 4, I2 = 0%) higher with UIC ≥ 150 μg/g, but not for I:Cr. UIC ≥ 150 μg/L was associated with lower risk of SGA (RR = 0.85, 0.75 to 0.96, p = 0.01, n = 13, I2 = 0%), but not with I:Cr. Conclusions: The main risk of bias was adjustment for confounding, with variation in urine sample collection and exposure definition. There were modest-sized associations between some measures of iodine status, birth weight, birth weight centile, and SGA. In pregnancy, we recommend that future studies report standardised measures of birth weight that take account of gestational age, such as birth weight centile and SGA. Whilst associations were modest-sized, we recommend maintaining iodine sufficiency in the population, especially for women of childbearing age on restricted diets low in iodide.

Prenatal Exposure to Mercury, Manganese, and Lead and Adverse Birth Outcomes in Suriname: A Population-Based Birth Cohort Study

Globally, adverse birth outcomes are increasingly linked to prenatal exposure to environmental contaminants, such as mercury, manganese, and lead. This study aims to assess an association between prenatal exposure to mercury, manganese, and lead and the occurrence of adverse birth outcomes in 380 pregnant women in Suriname. The numbers of stillbirths, preterm births, low birth weights, and low Apgar scores were determined, as well as blood levels of mercury, manganese, lead, and relevant covariates. Descriptive statistics were calculated using frequency distributions. The associations between mercury, manganese, and lead blood levels, on the one hand, and adverse birth outcomes, on the other hand, were explored using contingency tables, tested with the χ2-test (Fisher's exact test), and expressed with a p value. Multivariate logistic regression models were computed to explore independent associations and expressed as (adjusted) odds ratios (aOR) with 95% confidence intervals (CI). The findings of this study indicate no statistically significant relationship between blood mercury, manganese, or lead levels and stillbirth, preterm birth, low birth weight, and low Apgar score. However, the covariate diabetes mellitus (aOR 5.58, 95% CI (1.38-22.53)) was independently associated with preterm birth and the covariate hypertension (aOR 2.72, 95% CI (1.081-6.86)) with low birth weight. Nevertheless, the observed high proportions of pregnant women with blood levels of mercury, manganese, and lead above the reference levels values of public health concern warrants environmental health research on risk factors for adverse birth outcomes to develop public health policy interventions to protect pregnant Surinamese women and their newborns from potential long-term effects.

Family Income and Low Birth Weight in Term Infants: a Nationwide Study in Israel

OBJECTIVES

To explore the influence of income on Low Birth Weight (LBW), taking into account other socio-economic measurements.

METHODS

This retrospective cohort study is based on the Israel National Insurance Institute (NII) database. The study population included 58,454 women who gave birth between 2008 and 2013 to 85,605 infants. Only singleton births at term (gestational age in weeks = 37 and later) were included. Logistic regression models with a Generalized Estimating Equation approach were used in order to assess the independent effect of income and Socio-Economic Regional Index (SERI), maternal age, family status, population group and occupational status on LBW. In addition, sibling analysis was conducted to assess the influence of a change in income on birth weight (BW) among 21,998 women.

RESULTS

Lower income was associated with higher odds of LBW (odds ratio (OR) = 1.266; 95% CI:1.115-1.437. Immigrants from Ethiopia, Bedouins from the Negev, the youngest, the oldest, and single mothers had higher odds for LBW newborns. Compared to women whose income quartile had not changed between the most recent and the first births, for women who experienced a deterioration of three and two quartiles in family income, significantly lower birth weight was observed at the time point with lower income: 103 g (p = .049) and 71 g (p = .008), respectively. Improvement in income revealed an almost linear increase in birth weight.

CONCLUSIONS FOR PRACTICE

In an effort to prevent LBW associated mortality and diseases, interventions should be focused first of all on women from population groups who are disadvantaged.

Customized birthweight standard for a Polish population

Introduction

There is a growing body of evidence supporting the role of customized growth charts in improving detection of fetal growth restriction (FGR) and decreasing false positive diagnoses. The aim of the study is to produce a customised birthweight standard for Poland.

Material and methods

Maternal height and weight, ethnicity, gestational age, weight and sex at birth as well as pre-existing and gestational complications were collected. Coefficients were derived using a backwards stepwise multiple regression technique. Smallness for gestational age by the customised standard was compared with the in-use Fenton standard in assessing risk of adverse outcomes using relative risk with 95% confidence intervals.

Results

Data from 4,270 pregnancies were used as the study cohort. Fenton and customised SGA rates were 6.6% and 11.9%, respectively. The customised standard identified more cases that were at significantly increased risk of stillbirth, admission to neonatal intensive care or other neonatal complications, many of which were missed by the Fenton standard.

Conclusions

The analysis confirmed the physiological variables that affect birthweight in studies from other countries and was able to quantify additional pathological factors of high maternal age and pregnancy-induced hypertension. Comparison with the Fenton standard showed that adverse outcomes associated with SGA birthweight are better identified by the customised standard in a Polish population.

Health-Related Behaviors of Pregnant Women Residing in Urban and Rural Areas in Poland

The aim of this study was to evaluate the knowledge regarding a healthy lifestyle and prophylaxis during pregnancy among women from rural and urban areas and how this changed within a 5-year period. Analyses of the population of pregnant women in Poland were made using a questionnaire survey. The survey was conducted in the years 2010-2012 and 2017. Questionnaires from 6128 pregnant women were collected. The statistical analyses were conducted using IBM SPSS. The examined population was comprised of 41% women from rural areas and 59% women from urban areas. Alcohol consumption was lower among women from rural areas than among urban inhabitants in 2010-2012; in 2017 a trend of even lower consumption was observed. Folic acid supplementation was more broadly developed in the urban population; however, in 2017, higher percentage rates of both populations admitted taking folates before pregnancy. More women in urban than in rural areas performed physical activity during pregnancy, but the differences decreased in 2017. Knowledge of a healthy lifestyle and prophylaxis during pregnancy increased regardless of place of residence; however, the most evident change could be observed among women from rural areas.