Pregnancy Outcomes Based on Pre-Pregnancy Body Mass Index in Japanese Women

Abstract

ObjectiveTo verify whether body mass index (BMI) classification proposed by the Institute of Medicine (IOM) is valid in Japanese women.MethodA study was conducted in 97,157 women with singleton pregnancies registered in the Japan Society of Obstetrics and Gynecology (JSOG) Successive Pregnancy Birth Registry System between January 2013 and December 2013, to examine pregnancy outcomes in four groups stratified by pre-pregnancy BMI category according to the 2009 criteria recommended by the Institute of Medicine (IOM). The groups comprised 17,724 underweight women with BMI <18.5, 69,126 normal weight women with BMI 18.5–24.9, 7,502 overweight women with BMI 25–29.9, and 2,805 obese women with BMI ≥30. The pregnancy outcomes were also compared among subgroups stratified by a gestational weight gain below, within, and above the optimal weight gain.ResultsThe higher the pre-pregnancy BMI, the higher the incidences of pregnancy-induced hypertension, gestational diabetes mellitus, macrosomia, cesarean delivery, postpartum hemorrhage, and post-term birth, but the lower the incidence of small for gestational age (SGA). In all pre-pregnancy BMI category groups, excess gestational weight gain was associated with a higher frequency of large for gestational age and macrosomia; poor weight gain correlated with a higher frequency of SGA, preterm birth, preterm premature rupture of membranes, and spontaneous preterm birth; and optimal weight gain within the recommended range was associated with a better outcome.ConclusionThe BMI classification by the IOM was demonstrated to be valid in Japanese women.

Optimal weight gain in obese and overweight pregnant Japanese women

“…However, because the prevalence of SGA birth is generally lower in overweight pregnant women than in those with a normal pre-pregnancy weight [20], the prevalence was still only 6.4%, even in the small gain subgroup of the present study. Given that the lowest predicted probability of composite adverse outcomes, which showed significant differences compared to the IOM-recommended weight gain was observed in women with a weight gain of 0 kg, the optimal weight gain for Japanese overweight pregnant women ranges from 0 to 11.5 kg, which encompasses the IOMrecommended weight gain.…”

“…We considered ten main outcomes of interest, which are already known to be influenced by GWG [5][6][7][8][9][10][11][12][13][14][15][16][20][21][22][23][24][25][26][27]: small for gestational age (SGA), large for gestational age (LGA), low birth weight (LBW) (<2,500 g), macrosomia (≥4,000 g), gestational hypertension, preeclampsia, caesarean delivery, operative virginal delivery, umbilical artery pH <7.0, and an Apgar Score at 5 min <7. SGA and LGA neonates were defined as birth weights below the 10th percentile and above 90th percentile, respectively, after matching for gestational age and sex.…”

“…In our previous study entitled, "Pregnancy outcomes based on pre-pregnancy body mass index in Japanese women: POBMIJ Study," we reported that the IOM classification is also applicable to pregnant Japanese women because overweight (25 kg/m 2 ≤ BMI <30 kg/m 2 ) and obese (BMI ≥30 kg/m 2 ) women have different pregnancy outcomes. In addition, when pregnancy outcomes were compared among three groups of pregnant Japanese women with GWG below, within, and above the IOMrecommended weight gain, pregnant women with GWG within the IOM criteria had the best pregnancy outcomes among those with a BMI <30 kg/m 2 , whereas no differences were observed in those with a BMI ≥30kg/m 2 [20]. …”

Gestational weight gain in Japanese women with preeclampsia

“…Recently, some large studies in Japan investigated optimal GWG; [3][4][5][6] however, they may have insufficiently assessed the influence of GWG on the incidence of preeclampsia because GWG with preeclampsia is often due not only to eating habits, but also increased edema associated with renal and/or vascular endothelial dysfunction. Edema that accompanies preeclampsia often leads to weight gain just before the onset of preeclampsia, unlike that due to eating habits.…”

Relationship between Weight Pre-Pregnancy and Weight Gain during Pregnancy with Preterm Birth

“…Enomoto, et al showed that poor weight gain in pregnancy correlated with a higher frequency preterm birth, preterm premature rupture of membranes, and spontaneous preterm birth. In a study carried out with 4735 women, the risks for preterm and cesarean section were significantly higher in obese pregnant women [14,39]. A study conducted with 8266 women living in Amsterdam found that overweight and obesity have increased the threat for preterm labor risk and the preterm labor risk was more prevalent in smoking and immigrant women [40].…”