Intrapair Birth Weight Difference Research Articles

Twin birth weight discordancy in Nigeria

The perinatal outcomes for 56 birth-weight discordant twin pairs among 622 total twin deliveries that occurred over an 18-month period at the University of Ilorin Teaching Hospital are analyzed. The incidence of twin birth-size discordancy was 9%. Mean birth-weight (kg) was 2.78 ± 0.5 for the heavier twin and 1.90 ± 0.5 for the smaller twin, with a mean intra-pair birth-weight difference of 0.88 kg (31.7% of the heavier twin). Perinatal mortality in the smaller infants was increased above the mean for all twin births. There were no perinatal deaths among the heavier infants. Discordant twinning was associated with high parity and a disproportionate increase of unlike-sex pairs. These observations suggest the preponderance of discordancy in dizygotic twinning. Increased awareness and surveillance for discrepant twin pairs are suggested in order to improve perinatal outcome.

Disturbed intrauterine growth in twins: etiological aspects.

Factors presumed to influence intrauterine growth were analyzed among 192 twin pairs. Mean birthweight was considerably reduced compared to single pregnancies, and a high proportion of twins were growth retarded (12.4%). One fifth of the twin pairs presented an intrapair birthweight difference exceeding 20%. DZ twins were slightly heavier than the MZ, while dichorionic twins had a somewhat higher birthweight than the monochorionic. The intrapair weight differences were greater in twins with fused dichorionic placentae than in those with separate ones. The umbilical cord insertion seemed to influence intrauterine growth. Fetuses with velamentously or marginally inserted cords presented more frequently retarded growth than twins with centrally inserted umbilical cords. Though a total of 13 cases of twin transfusion syndromes were observed, these were not characterized by great intrapair weight differences.

Twin Birth Order, Birthweight and Birthweight Discordance: Any Relationship?

Aim: To assess the truthfulness of this common concept that first-born twins are usually heavier than their second-born siblings at birth. Methods: In a series of 104 sets of live-born twins, the birth weights of first-born twins were compared with those of their second-born siblings, after controlling for gender. Their intra-pair birthweight differences were determined and twin pairs whose birthweight difference was 15% or more were designated as discordant. Results: Twin I was heavier than Twin II in 61.5% of cases while Twin II was heavier than Twin I in 28.9% of cases. Twins I and II had equal birth weight in 9.6% of cases. Comparing the mean birthweight of the first-born-male twin with that of second-born- male twin, it was 2515 + 427g [95 % Confidence Interval, CI = 2402 - 2628) versus 2432 + 435g (95% C I = 2321 - 2543) p>0.05. The mean birthweight of first-born-female twin was 2326 + 445g (95% CI =2214 - 2439) while that of the second-born-female twin was 2325 + 501g (95% CI = 2197 - 2453) p>0.05. When the birthweight difference exceeded 750g, the probability that Twin I will be heavier than Twin II was 83.3% (5 of 6). Conclusion: Although the first-born twin was more often heavier than their second-born siblings, either could weigh more or less at birth. The larger the birthweight difference between growth-discordant twin pair, the greater the probability that the heavier twin would be delivered first. Keywords: Birth order relative birth weights, birthweight discordance, twins DOI: http://dx.doi.org/10.3126/njog.v6i1.5252 NJOG 2011; 6(1): 46-50

Importanza della Placentazione sul peso alla nascita dei Gemelli

SUMMARYThe Authors have analyzed the separate and combined influences of zygosity, placentation and sex on intra-pair birth-weight differences in 124 MZ and 124 DZ twin pairs. The highest influence on birth weight was found to be due separately to zygosity and placentation (respectively in cases of dizygosity and of a single placenta). The single placenta causes more circulatory unbalance and, as a consequence, more intrapair weight difference. This finding may help to explain the higher frequency of blighted fetuses in utero in MZ twin pregnancies and that of discordant congenital heart disease in female MZ twins.