Why do studies show different associations between intrauterine exposure to maternal smoking and age at menarche?

Purpose

Studies suggests that intrauterine exposure to maternal smoking both accelerates or delays age at menarche. We hypothesize that these opposing findings relate to different infant and childhood growth patterns across cohorts.

Female reproductive factors and risk of all-cause and cause-specific mortality among women: The Japan Public Health Center–based Prospective Study (JPHC study)

Purpose

We investigated the association between reproductive history and mortality from all and major causes among Japanese women.

Reproductive windows,genetic loci,and breast cancer risk

PurposeThe reproductive windows between age at menarche and age at first birth (standardized age at first birth) and from menarche to menopause (reproductive lifespan) may interact with genetic variants in association with breast cancer risk.MethodsWe assessed this hypothesis in 6131 breast cancer cases and 7274 controls who participated in the population-based Collaborative Breast Cancer Study. Risk factor information was collected through telephone interviews, and DNA samples were collected on a subsample (N= 1484 cases, 1307 controls) to genotype for 13 genome-wide association study-identified loci. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated, and P values for the interaction between reproductive windows and genotypes were obtained by adding cross-product terms to statistical models.ResultsFor standardized age at first birth, the OR was 1.52 (CI, 1.36–1.71) comparing the highest quintile with the lowest quintile. Carrier status for rs10941679 (5p12) and rs10483813 (RAD51B) appeared to modify this relationship (P = .04 and P = .02, respectively). For reproductive lifespan, the OR comparing the highest quintile with the lowest quintiles was 1.62 (CI, 1.35–1.95). No interactions were detected between genotype and reproductive lifespan (all P > .05). All results were similar regardless of ductal versus lobular breast cancer subtype.ConclusionsOur results suggest that the reproductive windows are associated with breast cancer risk and that associations may vary by genetic variants.     

15年间我国少数民族女生月经初潮年龄变化趋势

目的:分析我国少数民族女生月经初潮平均年龄及从1985～2000年15年间其月经初潮年龄的变化趋势。方法:收集到1985年、1991年和2000年的部分少数民族女生月经初潮平均年龄,比较其总体的变化趋势,并用统计软件作出趋势图。结果:蒙古族、维吾尔族、壮族、朝鲜族女生月经初潮平均年龄在15年来是逐年提前的,回族在1991～2000年这段期间女生月经初潮年龄出现后退现象。这5个少数民族均呈现出乡村提前的速度快于城市。结论:我国少数民族女生月经初潮平均年龄的"生长长期变化"趋势依然存在,但增长趋势在减缓。     

女生初潮年龄提前与黄体生成素受体基因Asp578Gly突变

目的研究黄体生成素受体(LHR)基因Asp578Gly突变与女生初潮年龄提前的关系,为青少年青春期发育研究提供依据。方法分层整群抽取无锡市177名初潮年龄提前(初潮年龄<11岁)女生,外周血提取DNA,用5’-CAC TGC TGG CTT TTT CAC TGTATT-3’和5’-TGA AGG CAG CTG AGA TGG CAA AAA-3’作引物,经常规PCR扩增后,用限制性内切酶MspⅠ消化,以检测LHR基因是否存在A1733G的碱基突变。结果初潮年龄提前组LH水平高于正常组(P<0.05),而两组FSH差异无统计学意义(P>0.05)。177名初潮年龄提前女生的LHR基因均未检测到Asp578Gly突变。结论 Asp578Gly突变与女性初潮年龄提前无直接关系。     

长春市小学女生月经初潮提前情况分析

目的了解东北某地区城市女孩月经初潮年龄提前的概况,探讨该概况与身高、饮食、遗传的关系,并给予心理、生理方面的健康指导。方法对长春市某重点小学4～6年级女学生1039人进行问卷调查,收集、整理并进行相关资料分析。结果月经初潮最小年龄为8．6岁。六年级月经来潮者121人,占29．66％,平均年龄11．10岁。五年级月经来潮者25人,占8．17％,平均年龄10．80岁。四年级月经来潮者6人,占1．84％,平均年龄9．10岁。结论城市女孩月经初潮时间呈现逐步提前趋势。与身高,饮食结构有较大定关系,与遗传因素的关系不明显,应引起重视。     

Age at menarche and the risk of operative delivery

Objectives: We sought to evaluate the impact of later menarche on the risk of operative delivery.

Population: We studied 38,069 eligible women (first labors at term with a singleton infant in a cephalic presentation) from the Norwegian Mothers and Child Cohort Study. The main exposures were the age at menarche and the duration of the interval between menarche and the first birth.

Methods: Poisson’s regression with a robust variance estimator.

Main outcome measures: Operative delivery, defined as emergency cesarean or assisted vaginal delivery (ventouse extraction or forceps).

Results: A 5 year increase in age at menarche was associated with a reduced risk of operative delivery (risk ratio [RR] 0.84, 95%CI 0.78, 0.89; p?p?p?=?.81). A 5 years increase in menarche to birth interval was associated with an increased risk of operative delivery (RR 1.26, 95%CI 1.23, 1.28; p?p?Conclusions: Later menarche reduces the risk of an operative first birth through shortening the menarche to birth interval. This observation is consistent with the hypothesis that the pattern and/or duration of prepregnancy exposure of the uterus to estrogen and progesterone contributes to uterine aging.