Biological aspects of twin pregnancy in Dundee

Twin's Birth-Order Differences in Height and Body Mass Index From Birth to Old Age: A Pooled Study of 26 Twin Cohorts Participating in the CODATwins Project

We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number of height and BMI measures from 0.5 to 79.5 years of age was 397,466. As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood. After adjusting the results for birth weight, the birth order differences decreased and were no longer statistically significant. First-born twins had greater BMI than the second-born twins over childhood and adolescence. After adjusting the results for birth weight, birth order was still associated with BMI until 12 years of age. No interaction effect between birth order and zygosity was found. Only limited evidence was found that birth order influenced variances of height or BMI. The results were similar among boys and girls and also in MZ and DZ twins. Overall, the differences in height and BMI between first- and second-born twins were modest even in early childhood, while adjustment for birth weight reduced the birth order differences but did not remove them for BMI.

Twin birth weight standards

OBJECTIVE

The aim of this study was to present customized twin-specific birth weight standards. The relative contribution of gestational age, maternal factors, twin factors and placental factors to the birth weight was evaluated in a multivariate approach.

SUBJECTS AND METHODS

Perinatal data were obtained from 10,177 live-born twins from the East Flanders Prospective Twin Survey. Of 8,454 twins (4,227 pairs), of whom all data were available, the birth weights at different gestational ages were analyzed using a non-linear multivariate gaussian regression.

RESULTS

All considered covariates influenced birth weight of twins significantly, with the exception of sex of the co-twin and mode of conception and delivery. At 37 weeks of gestation, a difference of >1 kg existed between favourable and adverse prenatal environment. Up to 40 weeks, sex, site of the umbilical cord, parity, and birth order had a greater influence on birth weight than zygosity, chorionicity and fusion of the placentas. From 34 weeks on, the birth weight of the second-born twin deviated and after 40 weeks, birth weight of monozygotic monochorionic twins dropped, while the other twins continued to grow.

CONCLUSION

Customized twin-specific birth weight standards, which take these covariates into account, offer the opportunity for a better assessment of the influence of birth weight of the twin on neonatal health in future research. Already the Developmental Origins of Health and Disease hypothesis showed that these prenatal conditions might also be important for the follow-up of the twin.

Multiple pregnancy in the Maltese population

This study analyses the multiple birth statistics for the Maltese Islands since 1959. Hospital twin births delivering during the period of 1983-1985 are analysed for a number of variables. The incidence of multiple pregnancy for the Maltese Islands appears to have decreased slightly since 1959 with an overall rate of 10.21 per 1000 maternities. The ratio of dizygotic to monozygotic twinning was computed to be 1.64. Patients with multiple pregnancies are shown to be generally elderly and multiparous. The pregnancy outcome is more likely to be complicated by an operative delivery, while the infant is more likely to be premature and of low birth weight. The perinatal mortality rate for multiple pregnancies is markedly in excess of that for singleton births.

Triplet pregnancy in Nigeria: socio-biologic aspects

A retrospective analysis of 20 triplet pregnancies not stimulated by clomiphene or gonadotrophins revealed a perinatal mortality of 26.3%. There were greater losses recorded in the case of mothers who had received no antenatal care than for those who had been seen before the babies' births. Triplet pregnancy in this series was associated with anemia, hypertension, postpartum hemorrhage and hydramnios. In Nigeria, where there is a high incidence of such pregnancy, it should be suspected more often than elsewhere. The authors recommend amnioscopy, amniocentesis and early resort to cesarean section as part of the antenatal regimen, with careful management of the third stage of labor to prevent postpartum hemorrhage.

The intrauterine growth of the biparietal diameter of twins

A series of 978 repeated ultrasonic measurements of the fetal biparietal diameter (BPD) assessed the growth of 119 twin pairs during the second half of pregnancy. The mean BPD values for each gestational week were close to the mean values for singletons. From the 32nd week, the BPD growth curves for twins deviated from that for singletons. The second twins' growth curve ran consistently below that of the first and fell away more from the 32nd week on. In 80% of the measurements, the first twin (defined as the twin in, or close to, the pelvic inlet) was the one with the largest BPD. The intrapair difference in BPD had no correlation to the intrapair difference in body length, head circumference, or birth weight. In 91 of the 119 twin pairs, zygosity was settled by sex, histological examination of placenta, or blood grouping. The longitudinally compiled BPD growth curves (678 BPD determinations) showed the curve for dizygotic twins consistently running above that of the monozygotic twins. The BPD differences between the first and the second twin remained also within mono- and dizygotic groups of twins.

Triplet pregnancy

A series of 14 triplet pregnancies has been analyzed. The older triplet mother had a better chance of fetal survival than the younger mother. Parity did not appear to have much effect on fetal survival but the maturity of the infants at birth had more influence than did birth weight, on their survival. The interval between the delivery of the second and third infants did not correlate with the poor prognosis for the last infant. Spontaneous breech delivery appeared to have a worse prognosis than assisted breech delivery. There was a high incidence of girls and they appeared to do better than the boys. There was a high incidence of monozygotic twin pairs in these triplet pregnancies.