Recreational exercise and occupational activity during pregnancy and birth weight: a case-control study.
OBJECTIVE
Our purpose was to investigate the impact of exercise and occupational activity on birth weight.


METHODS
This case-control study involved singleton infants at > or = 34 weeks' gestation without congenital anomalies. Case subjects had birth weights at <15th percentile for gestational age, and 2 control subjects were selected per case subject. Data were collected by self-completed questionnaire and analyzed by means of logistic regression.


RESULTS
Relative to those who participated in structured exercise 3 or 4 times per week during the third trimester, the odds of lower birth weight were substantially increased for those who exercised > or = 5 times per week (adjusted odds ratio, 4.61; 95% confidence interval, 1.73-12.32) and modestly increased for those at the other extreme, who engaged in structured exercise < or = 2 times per week (adjusted odds ratio, 2.64; 95% confidence interval, 1.29-5.39). Other factors of importance to birth weight were maternal height, prepregnancy body mass, pregnancy weight gain, smoking in the third trimester, and nulliparity.


CONCLUSIONS
Structured exercise frequency during late pregnancy is a determinant of birth weight.
Campbell
M K
MK
Department of Epidemiology and Biostatistics, The University of Western Ontario, London, Canada.
Mottola
M F
MF
D000328:Adult; D001827:Body Height; D001835:Body Weight; D016022:Case-Control Studies; D005314:Embryonic and Fetal Development / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age / Q000502:physiology*; D016015:Logistic Models; D008423:Maternal Age; D015999:Multivariate Analysis; D009790:Occupations; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D012044:Regression Analysis; D012307:Risk Factors; D011795:Surveys and Questionnaires; D015430:Weight Gain; D014937:Work / Q000502:physiology*