Objective Physiological as well as pathological variables influence birthweight. The aim of the present study was to examine perinatal outcome in relation to birthweight centiles applying a customised birthweight standard. Methods Two hundred and seventeen babies from high risk pregnancies were evaluated and classified as small or not small for gestational age according to two standards: 1. conventional Dutch birthweight centiles and 2. customised centiles which adjust individually for physiological variables like maternal booking weight, height and ethnic origin. Results Customisation of the weight standards resulted in identification of an additional group of infants who were small for gestational age, but not by the Dutch standards. These babies were associated with significantly more adverse perinatal events than those who were not small for gestational age as defined by a customised standard. Conclusions Adjustment of birthweight centiles for physiological variables significantly improves the identification of infants who have failed to reach the expected birthweight and who are at increased risk for adverse perinatal events.

Impaired fetal weight gain prior to birth is associated with adverse perinatal events suggestive of growth failure.

The assessment of fetal weight using ultrasound and an individually-adjusted standard is predictive of growth restriction and perinatal events associated with hypoxia or diminished reserve. The optimal cut-off value for predicting operative delivery for fetal distress or admission to the neonatal intensive care unit suggests that the 10th customized percentile is a good limit for clinical use.

Physiological as well as pathological variables influence fetal growth. This study was undertaken to assess the influence of physiological variables on fetal weight gain in a high-risk population with normal outcome. A total of 121 pregnancies had 3-13 (median 8) ultrasound scans in the third trimester. Estimated fetal weight was calculated according to standard formulae. The estimated fetal weight at 30, 34 and 38 weeks and growth per day in the last 2 weeks prior to delivery were calculated and compared between subgroups defined on physiological characteristics, such as maternal height, maternal weight, parity and fetal sex. There were differences in growth curves for each of the physiological parameters studied. Maternal height and weight were significantly related to the estimated fetal weight throughout the third trimester but there were no significant differences in growth per day in the last 2 weeks before birth. In contrast, subgroups defined by parity and fetal sex did not show significant fetal weight differences in the third trimester, but the daily growth rate prior to birth was significantly higher for multiparae and male fetuses. Physiological factors affect fetal weight gain and need to be taken into account when fetal growth is monitored in high-risk pregnancies.

The findings of the present study confirm those of previous studies that have found increased total plasma fibronectin levels in pregnancy-induced hypertensive disorders. This study discovered that in these women, total plasma fibronectin levels are elevated in the first trimester. Total plasma fibronectin appears to be a poor predictor of preeclampsia when measured in a general pregnant population. Therefore, total plasma fibronectin should not be used as a routine screening test in a low-risk population. However, obstetricians may use total plasma fibronectin values to help determine the relative risk of developing pregnancy-induced hypertensive disorders.