On the relationship between pregnancy weight gain and chorioamnionitis.

Chorioamnionitis refers to infection of the amniotic fluid by such agents as Streptococcus sp., E. coli and Ureaplasma sp. It has not only been linked to the risk of premature rupture of the membranes and preterm delivery, but also to increased morbidity and mortality among neonates born to mothers with such infections. The possible association between maternal gestational weight gain and chorioamnionitis was examined in data using a case sample of 62 and control sample of 168 Israeli women. Univariate analysis demonstrated a significant increase in the incidence of chorioamnionitis among mothers delivering before 33 weeks gestation who displayed inadequate gestational weight gain according to the IOM standards. Comparison of logistic regression analyses between mothers who developed chorioamnionitis at different stages of their pregnancies, controlling for the effects of maternal anthropometric, sociodemographic, and obstetric factors, showed that inadequate weight gain significantly increased the risk of chorioamnionitis among those delivering very prematurely. The differences in significant risk factors suggest the possibility that pre- and full-term chorioamnionitis may not have the same etiologies. Am. J. Hum. Biol. 9:545-553, 1997. © 1997 Wiley-Liss, Inc.

Obesity and the risk of toxaemia of pregnancy.

The purpose of the present study was to examine the relationship between severe pre-eclampsia/eclampsia (toxaemia) and obesity. We collected sociodemographic, anthropometric, medical and pregnancy outcome data from the hospital records of 248 Israeli women diagnosed with either pregnancy-induced or chronic hypertension, and compared these data to a control group of 236 women. Univariate analysis showed that while there exists a statistically significant positive association between obesity and hypertension (both pregnancy-induced and chronic) obesity presents no added risk to the development of toxaemia. Furthermore, we found a significant decrease in the rate of obesity among primigravid versus multigravid mothers with toxaemia superimposed on pregnancy-induced hypertension. On the other hand, primigravid mothers with PIH were at an increased risk of developing toxaemia as compared to multigravid women. These results suggest that obesity is not a significant factor in the development of toxaemia.

Path analysis of risk factors leading to premature birth.

The present study tested whether various sociodemographic, anthropometric, behavioral, and medical/physiological factors act in a direct or indirect manner on the risk of prematurity using path analysis on a sample of Israeli births. The path model shows that medical complications, primarily toxemia, chorioammionitis, and a previous low birth weight delivery directly and significantly act on the risk of prematurity as do low maternal pregnancy weight gain and ethnicity. Other medical complications, including chronic hypertension, preclampsia, and placental abruption, although significantly correlated with prematurity, act indirectly on prematurity through toxemia. The model further shows that the commonly accepted sociodemographic, anthropometric, and behavioral risk factors act by modifying the development of medical complications that lead to prematurity as opposed to having a direct effect on premature delivery. © 1996 Wiley-Liss, Inc.

Reliability of reliability coefficients in the estimation of asymmetry.

Although promising to provide insight into the interaction between genotype and environment, investigations into fluctuating asymmetry suffer from a lack of standardization in the reporting of measurement error. In the present paper we show, using both anthropometric and odontometric data, that the use of the reliability coefficient calculated for a bilateral measurement provides no indication of the reliability of the corresponding asymmetry estimate, because reliability of asymmetry depends on the relationship between measurement error and the difference between sides. Thus, we suggest that future investigations either provide reliability coefficients for asymmetry estimates specifically, or use methods that account for measurement error.

Selection on maternal and neonate size at birth.

Neonatal size is an important factor in determining the survivorship of infants within the first month of life. Because maternal size has an influence on neonatal size, selection should operate on those characters correlated with birth weight and gestational age, including maternal prepregnancy weight, height, and age. In the present study we use a path-analysis approach to examine the operation of selection on both neonatal and maternal size. We found that neonatal survivorship depends not only on the size of the infant at birth but also on a negative allometric relationship between the size of the neonate and the size of the mother. Thus, although the size of the mother has no direct effect on neonatal mortality, the mothers of surviving infants tend to be smaller relative to the size of their neonate. This may provide a mechanism whereby selection maintains a balance between maternal size and neonate size.