Division of Obstetrics and Gynaecology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Department of Obstetrics and Gynaecology in Linköping, County Council of Östergötland, Linköping, Sweden.
BMC Pregnancy Childbirth. 2013 Jan 16;13:6. doi: 10.1186/1471-2393-13-6.
During the last decades there has been a steady increase of twin births. A combination of improved medical treatment of preterm and small-for-gestational age children has contributed to a higher number of surviving twins. Prematurity is known to affect reproduction in a negative way. Few studies have focused on the potential effect twinning may have on future reproduction. Thus, the aim of this study was to investigate the effect of being born a twin compared to being born a singleton have on future reproduction.
In a national population-based register study, all individuals born between 1973-1983 who were alive and living in Sweden at 13 years of age (n = 1 016 908) constituted the sample. Data on each study subject's own birth as well as the birth of their first offspring, and parental socio-demographic factors were collected from Swedish population based registers. Hazard ratios and corresponding 95% CI was calculated using Cox proportional hazards model.
Twins, both men and women, had a reduced likelihood of reproducing compared to singletons (women: HR = 0.89, 95% CI = 0.86-0.93; men: HR = 0.92, 95% CI = 0.87-0.97). This difference in birth rates can only partly be explained by diverging birth characteristics. Amongst men and women born very preterm, twins had an increased likelihood of reproducing compared to singletons (women: HR = 1.25, 95% CI = 1.02-1.62; men: HR = 1.34, 95% CI = 1.01-1.78).
Twins have lower reproduction rates compared to singletons, which only to a certain degree can be explained by diverging birth characteristics.
在过去的几十年中，双胞胎的出生率稳步上升。早产儿和小于胎龄儿治疗水平的提高是导致存活双胞胎数量增加的原因之一。众所周知，早产会对生殖产生负面影响。很少有研究关注双胞胎出生可能对未来生殖产生的潜在影响。因此，本研究旨在调查与单胎出生相比，双胞胎出生对未来生殖的影响。
在一项全国性基于人群的登记研究中，所有在 1973 年至 1983 年期间出生且在 13 岁时仍在世并居住在瑞典的个体（n=1 016 908）构成了样本。从瑞典人口登记处收集了每个研究对象自身出生以及其第一个后代出生的信息，以及父母的社会人口统计学因素。使用 Cox 比例风险模型计算危险比和相应的 95%置信区间。
男性和女性双胞胎的生殖能力均低于单胎（女性：HR=0.89，95%CI=0.86-0.93；男性：HR=0.92，95%CI=0.87-0.97）。这种出生率的差异只能部分解释为出生特征的差异。在非常早产的男性和女性中，双胞胎的生殖能力高于单胎（女性：HR=1.25，95%CI=1.02-1.62；男性：HR=1.34，95%CI=1.01-1.78）。
与单胎相比，双胞胎的生殖率较低，这只能在一定程度上用不同的出生特征来解释。
