Obstetrics, Gynecology & Reproductive Sciences, University of California, San Francisco, San Francisco, CA.
Preterm Birth Initiative - California, University of California San Francisco School of Medicine, San Francisco, CA.
Prenat Diagn. 2021 Aug;41(9):1074-1079. doi: 10.1002/pd.5997. Epub 2021 Jun 27.
To determine the ratio of dichorionic (DC) to monochorionic (MC) twins by maternal age.
We reviewed all twin pregnancies undergoing first trimester screening (FTS) with nuchal translucency from April 2009 to December 2012 with sonographic determination of chorionicity. Cases were linked to newborn screening (NBS) results and zygosity estimated based on rates of fetal sex discordance. The ratio of DC to MC placentation by maternal age was calculated.
We identified 11,351 twin pregnancies with FTS and documented chorionicity. Among these, 7,861 (64.2%) had linked data on FTS and NBS to allow estimation of zygosity based on neonatal sex. Of these, 1,464 (18.6%) were MC and 6,406 (81.4%) DC. The MC twin rate remained constant while the DC twin rate increased with maternal age until 40y. At < 20y, 55% of twin pregnancies were monozygotic (MZ), as compared to 29% at ≥ 40y. Of MZ twins, 38% were DC at < 20y, while 53% were DC at ≥ 40y.
Our data suggest a relationship of both zygosity and chorionicity with maternal age. DZ twinning increased with maternal age, while among MZ twins, the proportion that were DC also increased with maternal age.
通过母亲年龄确定双绒毛膜（DC）与单绒毛膜（MC）双胞胎的比例。
我们回顾了 2009 年 4 月至 2012 年 12 月期间所有接受颈项透明层（NT）超声检查的双胎妊娠病例，以确定其绒毛膜性。这些病例与新生儿筛查（NBS）结果相关联，并根据胎儿性别不一致的比例估计其单合子性。按母亲年龄计算 DC 与 MC 胎盘的比例。
我们确定了 11351 例接受 FTS 检查且记录有绒毛膜性的双胎妊娠病例。其中，7861 例（64.2%）有 FTS 和 NBS 的关联数据，可根据新生儿性别来估计单合子性。这些病例中，1464 例（18.6%）为 MC，6406 例（81.4%）为 DC。MC 双胞胎的比例保持不变，而 DC 双胞胎的比例随着母亲年龄的增长而增加，直至 40 岁。在<20 岁时，55%的双胎妊娠为单合子（MZ），而≥40 岁时为 29%。在 MZ 双胞胎中，38%在<20 岁时为 DC，而 53%在≥40 岁时为 DC。
我们的数据表明，合子性和绒毛膜性都与母亲年龄有关。DZ 双胞胎的比例随着母亲年龄的增长而增加，而在 MZ 双胞胎中，DC 双胞胎的比例也随着母亲年龄的增长而增加。
