Aiming to show that delayed ovulation may induce MZ twinning, follicular maturation was induced in the rabbit by a small quantity of Pregnant Mare Serum Gonadotropin (16 UI four times): coitus, which induces ovulation in the rabbit, was delayed 60 hours after the last injection. From the 387 blastocysts obtained after this treatment, 6 (1.5%) were pairs of MZ twins, twinning being otherwise exceptional in the rabbit. Other anomalies were shown by the embryos, apparently related to a deficient quality of the eggs: high embryonic mortality (62% vs. 27% in controls) and chromosomal anomalies (20%) such as trisomies, triploidies, and chimaeras. The relation between MZ twinning, chromosomal anomalies, and embryonic mortality induced by delayed ovulation, could be connected and related to the poor perinatal conditions frequently observed in human MZ twins.
Diabetes, whether or not it is insulin deficient, is frequently associated with vascular complications during pregnancy. It is accepted nowadays that the uterine artery velocity waveform is predictive concerning pregnancy-induced hypertension (PIH) and its complications. It thus seemed interesting to analyse the predictivity of vascular complications of diabetes by using uterine artery velocity waveforms. We have thus explored 37 diabetic patients [group 1: insulin-deficient diabetes (IDD), n = 10; group 2: gestational IDD, n = 6; and gestational non-IDD, n = 21). We have found vascular complications for 10 patients, divided between all 2 groups: 2 preeclampsia, 2 fetal suffering before any labour, 2 cases of intra-uterine growth retardation (including a trisomy 18) and 5 PIH. The uterine artery velocimetry measurement has been found to be pathological 5 times, and always in patients who later developed vascular complications. Among this selected population and excluding the trisomy 18, the sensitivity is of 44.5%, the specificity of 100%, the positive predictive value of 100%, and the negative predictive value of 84.3 %. If these results are confirmed, this examination could be an excellent marker of the vascular risk and thus would have its place during systematic survey of pregnancies complicated by diabetes.
A total of 116 cases of multiple pregnancy has been observed in a 5-year period. MZ twin pregnancies appear to be significantly increased in the maternal age group 31-35. Also significant is the higher frequency of abnormal cycles in MZ twin pregnancies. Family incidence of twins is more significant in mothers of DZ as compared to MZ twins.
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