BIRTH-WEIGHT DISCORDANCE, INTRAUTERINE GROWTH-RETARDATION AND PERINATAL OUTCOMES IN TWINS

In a population-based study, the association between twin perinatal ou tcome, birth weight discordance and intrauterine growth retardation (I UGR) was investigated. Mortality was examined in 1,145 twin pairs, and neonatal morbidity was studied in 315 live-born pairs. In this study, birth weight discordance was defined as greater than or equal to 25% of the weight of the heavier twin, and IUGR was defined as <10th perce ntile of gender- and gestational age-specific singleton birth weight. In univariate analyses IUGR and discordance were associated with morta lity but not with morbidity. When twins were categorized by discordanc e and IUGR simultaneously, stillbirths were associated with IUGR, whil e discordant twins had elevated risks of early neonatal death. In mult iple logistic regression analyses, which also included gestational age , mode of delivery, birth order, birth weight discordance and IUGR, lo w birth weight was the single consistent factor associated with elevat ed risks of mortality and morbidity. For every 250-g increase in birth weight, the risks for each condition examined fell by about 40%. Disc ordance was an independent risk factor only for hypoglycemia, while IU GR was not associated with any neonatal outcome. Birth weight itself s eems to be the most important factor associated with perinatal outcome in twin births. Therefore, the weight of the individual fetus should be the focus of concern of the medical profession in the effort to red uce adverse outcomes in twin pregnancies.