[Relationship between dietary acid load in late pregnancy and infant body mass index for age Z score trajectories].

Objective: To explore the relationship between dietary acid load during late pregnancy in pregnant women and body mass index for age Z score(BMIZ) trajectories in infants.

Methods: From September 2010 to November 2011, a total of 468 women in late pregnancy in Guangzhou were recruited as the study subjects, and their offspring were followed up to 1 year old after delivery. Pregnant women were required to complete a basic situation questionnaire and a 3-day 24-hour dietary review survey in late pregnancy. They were also asked to complete a questionnaire on delivery and fetal health status after delivery. The dietary acid load during late pregnancy was calculated using potential renal acid load(PRAL), net endogenous acid production(NEAP), and animal protein to potassium ratio(A∶K ratio). The subjects were then grouped according to the quartiles for each indicator. The weight and length of infants at birth, 1, 3, 6 and 12 months old were prospectively tracked. The BMIZ were calculated and the BMIZ trajectories of infants were analyzed by latent class growth model(LCGM). Multiple logistic regression was used to analyze the relationship between dietary acid load during late pregnancy and BMIZ trajectories of infants.

Results: The median and quartiles of PRAL in late pregnancy were 28.02(21.88, 36.51) mEq/d, and the values of NEAP and A∶K ratio were (81.58±15.41) mEq/d and 22.62±6.80, respectively. A significant negative correlation was identified between dietary acid load and the intake of vegetables, fruits, and legumes(P<0.01). A significant positive correlation was identified between dietary acid lood with the intake of eggs, poultry, livestock, and seafood(P<0.01). According to the latent class growth model, three types of infant BMIZ trajectory groups were identified: the slower growth group(n=52), the appropriate growth group(n=307) and the faster growth group(n=54). Among the infants in the faster growth group, their mothers' late pregnancy NEAP was lower than that of the remaining two trajectory groups(P<0.05). Multiple Logistic regression analyses demonstrated that pregnant women in the highest quartile of late-pregnancy NEAP(OR=4.03, 95% CI 1.01-16.14) and A∶K ratio(OR=4.04, 95% CI 1.30-12.59) were more likely to have offspring with a slower growth trajectory compared with those in the lowest quartile.

Conclusion: Higher dietary acid loads in late pregnancy, particularly elevated levels of NEAP and A∶K ratio, have been associated with slower growth patterns in infants.