PubMed · 83505
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J D Erickson, T Bjerkedal. 1979-01-06. Interval between pregnancies.. https://doi.org/10.1016/s0140-6736(79)90502-6
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The effects of birth order, presentation and method of delivery on neonatal mortality and neurodevelopmental outcome in nondiscordant low birthweight ( < 2500 g) twin gestations were evaluated. Sixty-four sets of twins were included in the study; 29 sets were in vertex/vertex presentation (Group I), 25 sets in vertex/breech (Group II) and in 10 pregnancies the first twin was nonvertex (Group III). The rate of favorable neonatal outcome (survival and normal neurodevelopmental outcome after a 2-year follow-up) was lower in pregnancies in which at least one twin was in nonvertex presentation (50/70 vs. 52/58 P = 0.02). However, after adjustment by multiple logistic regression analysis for the effects of gestational age, birthweight, birth order and educational level of the mother, this difference was not statistically significant (odds ratio = 0.6; 95% confidence interval 0.44 to 5.9; P = 0.5). In pregnancies in which at least one of the twins was in nonvertex presentation, delivery by cesarean section did not affect the rate of favorable neonatal outcome (odds ratio = 1.8; 95% confidence interval 0.48 to 12.9; P = 0.8). The results of this study suggest that in low birthweight twin gestations, method of delivery in relation to fetal presentation has little or no effect on neonatal mortality and subsequent neonatal neurodevelopmental outcome.
The 4275 births to women of native ancestry that took place on the island of St Barthélemy, French West Indies between 1878 and 1970 were analyzed according to the sex of the child, the year of birth, maternal age, maternal parity, paternal age and the number of children the father already had to determine the effects of these variables on rates of perinatal death, death before age 1 and death before age 5. The year of birth, the number of children the father already had, and maternal parity influenced death before age 1 and death before age 5. The sex of the child also influenced the probability of dying in the first year of life but not the first 5 yr of life when the other variables were controlled. Perinatal deaths were influenced only by the sex of the child, but even this effect disappeared when the other variables were controlled.
Twinning rates in all of Japan for 1951-1968 and 1974-1990 were analyzed using data from vital statistics of Japan. The twinning rate per 1,000 births was 6.43 in 1951 and remained nearly constant until 1968, then decreased to 5.79 in 1974 and gradually increased to 7.00 in 1990. The MZ twinning rate increased slightly up to 1966, but decreased thereafter, whereas the DZ rate declined over the entire period. As for maternal age, the DZ rate increased up to the age group 35-39 and decreased thereafter. The same tendency is seen in the MZ rate, but the maternal age effect is less marked than in DZ twins. The same tendency is also seen in the overall rate for 1975-1985. As for geographical variations, the MZ and DZ rates were computed in each prefecture for 1955-1959 and in 1974. The DZ rate increased from a low level in the southwest Japan to a high level in the northeast for both periods, whereas the MZ rate was rather constant in 1974 throughout Japan. As for seasonal variation, the highest rates per 1,000 births for MZ(4.56) and DZ(2.20) twins were seen in April, with the lowest rate in September (3.69) for MZ twins and in July (1.71) for DZ twins.