Risks for the Foetus
Regardless of whether conception in women with TS is spontaneous or assisted, increased rates of spontaneous abortion and foetal abnormality have been described. In a review of 160 pregnancies in 74 women with TS, 29% resulted in miscarriage, 20% were associated with foetal anomalies such as TS and Down syndrome and 7% resulted in perinatal foetal death. In a Danish study, 6 (24%) of 25 offspring of TS women had an abnormal karyotype.
Spontaneous abortion may be due to abnormalities in foetal chromosomes or to an abnormal uterine environment. The uterus may be structurally abnormal (e.g. bicornuate), small due to delayed oestrogen replacement at puberty, or endometrial receptivity may be poor due to long-term hypo-oestrogenism, which should be avoided.[26–28] In 86 women with TS, 31% were found to have an immature uterus and 20% had not taken regular oestrogen. Uterine size was associated with history of spontaneous puberty, and duration and type of hormone replacement – oestradiol-based regimens were better than oral contraceptive-based regimens.
Approximately 22–50% of the offspring of TS women have intrauterine growth restriction, low birth weight and prematurity. These may be due to primary factors associated with the TS mother, or iatrogenic factors such as late-onset maternal oestrogen therapy and resultant small uterine size.[3,29,30]
Anomalies of the X chromosome can be inherited. Women who have X monosomy or structural anomalies of the X chromosome may produce oocytes with the sex chromosome anomaly, resulting in an affected zygote and ensuing spontaneous abortion or offspring with TS.
In view of the risk for foetal anomalies, antenatal diagnostic testing should be offered to all pregnant TS women and the pregnancies should be regarded as high risk.
Clin Endocrinol. 2013;79(5):606-614. © 2013 Blackwell Publishing