Abstract: Objective To evaluate the relationship between timing of gestational weight gain and maternal and neonatal outcomes in pregnant women with polycystic ovary syndrome (PCOS).Methods A retrospective study was conducted on the data involving the baseline characteristics, weight changes during pregnancy, and pregnancy outcomes of 714 pregnant women with PCOS. According to the recommendations of the 2009 Institute of Medicine (IOM) guidelines, we classified weight gain in the first- and second- trimester (before 28 weeks) into the inadequate, adequate and the excessive weight gain group, weight gain in the third- trimester was classified according to whether it was below, at or above the recommended weight gain. Chi-square test and multivariable Logistic regression analysis were performed to investigate the associations between the timing of gestational weight gain and perinatal outcomes. Results Compared with PCOS women who gained adequate weight gain in the first- and second-trimester, those who gained inadequate weight gain in the first- and second- trimester showed the lowered risk of hypertension disorders of pregnancy (HDP)(OR=0.29,95%CI:0.15-0.56), macrosomia (OR=0.33,95%CI:0.14-0.76)and large for gestational age (LGA)(OR=0.59,95%CI:0.35-0.99). Those with inadequate weight gain in the first- and second-trimester didn't show an increased risk of small for gestational age (SGA) (OR=0.69,95%CI:0.13-3.58) birth. Women who gained excessive weight gain in the first- and second-trimester showed an increased risk of LGA birth(OR=1.84,95%CI:1.18-2.88). Gestational weight gain in the first- and second-trimesters did not appear to be associated with gestational diabetes mellitus (GDM). Higher weight gain in the third-trimester was associated with an increased risk of HDP(OR=3.19,95%CI:1.41-7.21) (for women with adequate gestational weight gain in the first- and second-trimesters) or the occurrence of the HDP was on the rise (for women with inadequate/excessive gestational weight gain in the first- and second-trimesters), higher weight gain in the third-trimester was associated with an increased risk of LGA(OR=3.15,95%CI:1.41-7.04) (for women with excessive gestational weight gain in the first- and second-trimesters) or the occurrence of the LGA was on the rise (for women with inadequate/adequate gestational weight gain in the first- and second-trimesters), regardless of early gestational weight gain. -Conclusions- Excessive weight gain in each trimester of pregnancy in PCOS pregnant women increased the risk of fetal overgrowth. However, some unique trends existed in PCOS pregnant women. Specifically, inadequate gestational weight gain in the first- and second-trimester showed a protective effect on HDP and it did not seem to increase the risk of SGA birth. However, the potential impact on the long-term health of the offspring is still unclear. It is necessary to figure out whether pregnant women with PCOS need less weight gain recommendations before the third-trimester than general pregnant women.

Key words: polycystic ovary syndrome, pregnancy, weight changes, pregnancy outcome