The relation between inter-twin birth weight discordance and total twin birth weight

Citation
I. Blickstein et al., The relation between inter-twin birth weight discordance and total twin birth weight, OBSTET GYN, 93(1), 1999, pp. 113-116
Citations number
7
Categorie Soggetti
Reproductive Medicine","da verificare
Journal title
OBSTETRICS AND GYNECOLOGY
ISSN journal
00297844 → ACNP
Volume
93
Issue
1
Year of publication
1999
Pages
113 - 116
Database
ISI
SICI code
0029-7844(199901)93:1<113:TRBIBW>2.0.ZU;2-B
Abstract
Objective: We tested the hypothesis that the frequency of growth discordanc e among twins is not related to the uterine capacity for carrying twins. Method: We counted and compared the frequencies of birth weight discordance of more than 25% in an unlike-sexed twin cohort (n = 1244) and in a popula tion-based twin cohort (n = 7570) across the deciles of the total twin birt h weight (twin A + twin B) distribution. The birth order of the heavier twi n was noted. Results: Similar frequencies of discordant pairs were found in both cohorts (11% and 12%, respectively; Mantel-Haenszel chi(2) test: P = .131, odds ra tio (OR) 0.9, 99% confidence interval (CI) 0.67, 1.11; Woolf test for heter ogeneity: two-tailed P = .472). In the discordant pairs, twin A was conside rably more often the heavier twin in all birth weight deciles (unlike-sexed cohort: P < 10(-8), OR 5.9, 99% CI 3.0, 11.7; population-based cohort: P < 10(-8), OR 3.1, 99% CI 2.3, 4.0), and in both cohorts (inter-cohort differ ence: P = .109, OR 1.4, 99% CI 0.83, 2.32). Both cohorts showed a similar n onlinear trend: given that X = decile order, discordance decreased as a fun ction of 22.0 - 6.54 In[X] for the unlike-sexed twins cohort and 23.0 - 8.1 8 In[X] for the population-based cohort, with r values of 0.967. Conclusion: The more favorable the uterine milieu for carrying twins, the s maller the likelihood of discordant twin growth. Birth order of the heavier twin appears to be an integral part of the discordance phenomenon. The sim ilarity of the cohorts suggests that these conclusions are valid for both l ike and unlike-sexed twins. (C) 1999 by The American College of Obstetricia ns and Gynecologists.