Activity levels in pregnant New Zealand women: relationship with socioeconomic factors, well-being, anthropometric measures, and birth outcome.

Activity during pregnancy has health implications for mother and child. The aim of this prospective cohort study was to examine changes in activity levels during pregnancy; the influence of socioeconomic factors and well-being on activity, and the influence of activity on maternal anthropometric measures and birth outcome. Twenty-four hour activity diaries were collected for 3 d in months 4 and 7 of pregnancy in 197 volunteers. Anthropometric measures and questionnaires to determine personal details were collected at these times and 2 months post-partum. Health records were used to supply infant measures. The time spent on each activity category was calculated, and used to calculate overall daily metabolic equivalents (METs). Low socioeconomic (SES) group 24 h activity levels were significantly higher than for high SES or welfare groups (p = 0.013). Activity declined throughout pregnancy in all groups (p = 0.002). Women with children had higher 24 h activity, spending 41% more time walking and (or) on housework than nulliparous women (p = 0.013). Reduced well-being was associated with lower levels of activity. Sleep and lying down time influenced 2 month post-partum body mass (upper quartile gained 2.54 kg, lower quartile lost 0.24 kg, p < 0.001). Mean infant gestational age increased with increasing 24 h activity (p = 0.047). No infants were born prematurely to mothers who spent more than 190 min/d walking or doing housework activities in month 4. Probability of infant admission to the neonatal intensive care unit (NICU) declined with time spent walking or doing housework in month 4 (p = 0.007). Mean (SE) birth weight was 3883 (+/-165) g in the 10% of women spending less than 530 min sleeping or lying down per day, compared with 3413 (+/-104) g in the 10% of women spending 725 min or more sleeping or lying down. Socioeconomic factors were therefore important influences on activity levels during pregnancy. Inactivity, especially in early pregnancy, was associated with more maternal weight retention at 2 months post-partum and a greater probability of admission to NICU and premature delivery.