Age at menarche and risk of adverse obstetric outcomes during the first childbirth in Japan: The Japan Environment and Children's Study

Abstract

Aim Age at menarche is used as a risk indicator of gestational diabetes mellitus, preterm birth, and fetal growth. However, little is known regarding the age impact on obstetric outcomes among nulliparous women. This study investigated whether menarche age was correlated with obstetric outcomes among nulliparous women. Methods We analyzed the data obtained for 37 645 singleton pregnancies between 2011 and 2014 in the Japan Environment and Children's Study. Age at menarche was categorized into the ≤9‐, 10‐, 11‐, 12‐, 13‐, 14‐, and ≥15‐year‐old groups (n = 363, 3155, 8390, 11 164, 6713, 5446, and 2414, respectively). We calculated the relative risk for cases of preterm birth <37 weeks, low birthweight <2500 g, small for gestational age, early and late‐onset hypertension disorders of pregnancy, and early‐ and late‐diagnosed (diagnosed < or ≧ 24 weeks) gestational diabetes mellitus using a reference of 12 years at menarche. Results Women with an age at menarche ≤9 years showed an increased incidence of developing early‐diagnosed gestational diabetes mellitus (relative risk: 2.42; 95% confidence interval: 1.05–5.60). A high body mass index before pregnancy increased the risk of developing gestational diabetes mellitus. Conclusions Age at menarche helped in assessing the risk of early‐diagnosed gestational diabetes mellitus among nulliparous women. Future studies are needed to clarify the underlying mechanisms. This study is the first to use data from the largest prospective birth cohort study of Japan and to investigate the relationship between menarche age and obstetric outcomes among nulliparous women.

Optimal gestational weight gain to reduce the risk of hypertension disorders of pregnancy among women with obesity: A single tertiary referral center study in Japan

“…In our institution, HDP is defined as new‐onset hypertension occurring after 20 weeks of gestation, 14 and is further categorized as early‐onset (Eo)‐HDP (occurring at <34 weeks of gestation) and late‐onset (Lo‐) HDP (occurring at ≥34 weeks of gestation). Gestational age was determined in the early stages of pregnancy based on the last menstrual period and/or ultrasound examination.…”

“…Gestational age was determined in the early stages of pregnancy based on the last menstrual period and/or ultrasound examination. The definition of GDM used in our institution has already been reported elesewhere 14 LD was defined as follows: a case with the cephalic presentation without a history of cesarean section (CS) and either operative vaginal delivery with several trials of maternal effort, due to arrest of the active phase for at least 4 h when the dilation of the cervix was 10 cm with or without an augmentation agent, or no progress in cervical dilation despite clinically adequate effective labor, irrespective of augmentation, such as the use of oxytocin or amniotomy 15 . Methods of delivery were categorized as emergent cesarean section or other.…”

“…Maternal background information retrieved included maternal age at delivery, maternal smoking before pregnancy, method of conception, parity, BMI before pregnancy, gestational weight gain during pregnancy, and medical conditions before pregnancy, such as hypertension. Obstetric outcomes included HDP, gestational age at the time of occurrence of HDP, 12,13 gestational diabetes mellitus (GDM), 14 labor dystocia (LD), and mode of delivery. We excluded cases with multiple pregnancies, maternal hypertension at the time of pregnancy, prepregnancy BMI < 30 kg/m 2 , and those with missing BMI data.…”

The Association between Early Menarche and Small for Gestational Age Birth

“…However, the early menarche-SGA birth association is under researched and limited to studies conducted outside of the U.S. In fact, to our knowledge only one study conducted in the last 20 years has examined this relationship, and results suggested no association between early menarche and SGA (menarche at age nine, RR: 0.99, 95% CI: 0.62-1.59; menarche at age 10, RR: 0.87, 95% CI: 0.73-1.05; menarche age 11, RR: 1.04, 95% CI: 0.92-1.18) (Kanno et al, 2022). As this study was also conducted in Japan, it is unclear if the findings also extend to U.S. women.…”

“…Women self-reported age at menarche during an inperson interview conducted by trained NSFG staff. Consistent with previous studies, women were considered exposed if menarche occurred <12 years old (Kanno et al, 2022). The outcome of interest was SGA birth.…”