Is birth weight associated with pregestational maternal BMI? BRISA Cohort, Ribeirão Preto, Brazil

Given the increase of women with excess weight or obesity and its possible effects on birth weight, the present study aimed to investigate the association between pregestational maternal body mass index (BMI) and birth weight in a birth cohort from Ribeirão Preto, SP, Brazil. This was a prospective study conducted on 1362 mother-child pairs involving singleton births. The women were evaluated using standardized questionnaires during the second trimester of pregnancy and at the time of childbirth. Information about the newborns was obtained from their medical records. The dependent variable was birth weight, categorized as low, adequate, or high. The independent variable was pregestational maternal BMI, categorized as malnutrition, adequate weight, overweight, and obesity. A multinomial regression model was used to estimate the crude and adjusted relative risk (RR) of low and high birth weight. A high frequency of pregestational excess weight (39.6%) was detected and found to be independently associated with high birth weight (RR=2.13, 95%CI: 1.19-3.80 for overweight and RR=3.34, 95%CI: 1.80-6.19 for obese pregnant women). There was no association between pregestational malnutrition and low birth weight (RR=1.70; 95%CI: 0.81-3.55). The present data showed a high rate of women with excess pregestational weight, supporting the hypothesis that pregestational BMI may contribute to high birth weight babies and indicating the need for actions aiming to prevent excessive weight in women at reproductive age.

鉴于超重或肥胖女性比例持续上升，且其可能对新生儿出生体重产生潜在影响，本研究旨在探讨巴西圣保罗州里贝朗普雷图市某出生队列中，孕前母亲体质量指数（Body Mass Index，BMI）与新生儿出生体重之间的关联。本研究为一项前瞻性研究，共纳入1362对单胎妊娠的母婴对子。研究对象在妊娠中期及分娩时接受标准化问卷评估；新生儿相关信息则从其病历档案中提取。本研究的因变量为新生儿出生体重，分为低出生体重、适宜出生体重及高出生体重三类；自变量为孕前母亲体质量指数，分为营养不良、体重正常、超重及肥胖四类。本研究采用多项回归模型，估算低、高出生体重的粗相对危险度（Relative Risk，RR）与校正后相对危险度。研究检出孕前超重及肥胖比例高达39.6%，且该状态与高出生体重存在独立关联（超重孕妇的RR=2.13，95%置信区间：1.19~3.80；肥胖孕妇的RR=3.34，95%置信区间：1.80~6.19）。孕前营养不良与低出生体重则未发现显著关联（RR=1.70，95%置信区间：0.81~3.55）。本研究数据显示孕前超重及肥胖女性占比偏高，验证了孕前体质量指数可能与新生儿高出生体重相关的假说，并提示需采取干预措施，预防育龄女性体重过度增长。