Studies of Białystok and Zambrów (Poland) newborns, their families, and duration of pregnancies from which they were born.

The paper presents a preliminary analysis of the properties of the 1034 families of newborns examined in 1977-78 in Białystok and Zambrów. This analysis also involves the course of pregnancy and delivery, placenta properties, and some traits indicative of the new born status (including diseases, malformations, trauma, blood groups, serological conflict, adaptability, mortality). According to the results the mean age at mother's maturation was 14.4 years, the most frequent season of the menarche was summer (38.2%). The mean age of mothers at delivery was 26.3 years, and that of fathers 29.3 years. The mean stature was 161.4 cm for mothers and 173.6 cm for fathers. The average increase in mother's body weight over the 20-week pregnancy period was 6.4 kg. Mean birth weight was 3.48 kg in boys and 3.36 kg in girls, mean placenta weight was 493.6 g of male, and 484.7 g of female fetuses. The majority of newborns was healthy. Only about 1.3% of the newborns suffered from typical diseases of newborns, 1% had inborn malformations, and 1.4% were injured.