Effects of maternal exercise during pregnancy on neonatal weight and subcutaneous fat thickness
孕妇的平均年龄为（28.5±3.8）岁，孕前BMI为（21.4±3.0）kg·m−2。男婴比女婴略多（54.3% vs 45.7%），新生儿的体重为（3374.0±427.5）g。腹部、肩胛、肱三头肌的皮下脂肪厚度分别为（4.4±1.3）、（5.4±1.4）、（6.0±1.5）mm，皮下脂肪厚度之和为（15.8±3.9）mm。在孕早期和孕中期，每周步行4 d及以上的孕妇分别占77.3%和88.7%；平均每天步行时长分别为（36.9±27.2）、（43.3±26.3）min；累计运动指数分别为25.6±17.7和35.9±21.1。多重线性回归分析结果显示：在孕中期，累计运动指数与新生儿腹部（
b=−0.006，95% CI：−0.010~−0.003）、肩胛（ b=−0.005，95% CI：−0.009~−0.002）、肱三头肌（ b=−0.006，95% CI：−0.010~−0.002）和皮下脂肪厚度之和（ b=−0.018，95% CI：−0.028~−0.007）均呈负相关（ P<0.05）；在孕早期和孕中期，累计运动指数与体重的关联无统计学意义。分层分析发现，孕中期的累计运动指数与皮下脂肪厚度的负向关联在男婴和母亲孕前BMI正常的新生儿中仍然具有统计学意义（ P<0.05）。 结论
Exercise during pregnancy is closely related to maternal and infant health. Previous studies in developed countries have linked maternal exercise during pregnancy with newborn body weight as well as subcutaneous fat thickness. However, the relevant studies in China are limited, and the conclusions remain inconsistent.
To investigate the effects of maternal exercise during pregnancy on neonatal weight and subcutaneous fat thickness.
Based on the Shanghai Birth Cohort, 959 maternal-infant pairs were included in this study. The International Physical Activity Questionnaire was used to collect average weekly frequency and daily minutes of walking in the first and second trimesters, and entropy weight method was used to calculate the cumulative exercise index in the two trimesters. Birth weight was measured using a calibrated weigh scale. Subcutaneous fat thickness was measured at abdomen, scapula, and triceps with a Harpenden skinfold caliper for all newborns and the sum of the thickness for the three sites was then calculated. A multiple linear regression model was employed to estimate the relationships of cumulative exercise index during pregnancy with neonatal body weight and subcutaneous fat thickness. Subgroup analyses stratified by pre-pregnancy body mass index (BMI) and sex of newborns were also performed.
The mean age of pregnant women was (28.5±3.8) years, and the pre-pregnancy BMI was (21.4±3.0) kg·m−2. Newborn boys were slightly more than newborn girls (54.3% vs 45.7%), and the neonatal weight was (3374.0±427.5) g. The means of newborns' abdominal, scapular, and triceps subcutaneous fat thickness were (4.4±1.3), (5.4±1.4), and (6.0±1.5) mm, respectively, and the sum of subcutaneous fat thickness was (15.8±3.9) mm. In the first and second trimesters, 77.3% and 88.7% of pregnant women walked 4 d per week and more, respectively; the daily minutes of walking was (36.9±27.2) min and (43.3±26.3) min, respectively; the cumulative exercise index was 25.6±17.7 and 35.9±21.1, respectively. The results of multiple linear regression analysis showed that the cumulative exercise index in the second trimester was negatively associated with newborns' abdominal (
b=−0.006, 95% CI: −0.010-−0.003), scapular ( b=−0.005, 95% CI: −0.009-−0.002), triceps ( b=−0.006, 95% CI: −0.010-−0.002), and their sum of ( b=−0.018, 95% CI: −0.028-−0.007) subcutaneous fat thickness ( P<0.05); in the first and second trimesters, however, the relationship between maternal cumulative exercise and newborns' body weight was not significant. The results of stratified analyses showed that the negative associations between maternal cumulative exercise index and newborns' subcutaneous fat thickness for the second trimester remained significant in the subgroups of boys and neonates whose mothers had normal pre-pregnancy BMI ( P<0.05). Conclusion
Cumulative exercise index in the second trimester is negatively correlated with the neonatal thickness of subcutaneous fat, and the association may be altered by neonatal sexes and maternal pre-pregnancy BMI levels.