Serum zinc and serum copper concentrations during early pregnancy in 84 consecutive primigravidae were correlated to other haematological factors and were also correlated to complications of labour and/or complications affecting the infant. In women with complications such as abnormal labour or atonic bleeding, serum zinc concentrations were significantly reduced (p less than 0.001) during early pregnancy. Women who gave birth to immature infants also showed significantly lower serum zinc in early pregnancy (p less than 0.01). Women delivered in the 37th week or earlier or in the 43rd week or later showed significantly lower serum zinc during early pregnancy (p less than 0.005) compared to women delivered in the 40th week. One infant showed a congenital heart defect (ventricular septum defect and preductal coarctation of aorta). Her mother showed the lowest serum zinc concentration recorded in the 13th week, but no other abnormal findings. Compared to women with abnormal labours and/or immature infants, mothers with normal deliveries and normal deliveries and normal infants showed significantly higher serum zinc values (p less than 0.001) and significantly lower serum copper concentrations (p less than 0.025) during early pregnancy. A notably high incidence of complications affecting mothers and infants has been recorded among women with low serum zinc. Similarities to effects of experimental zinc deficiency in animals are striking. If a low serum zinc reflects a state of deficiency, and this seems to be the case, zinc deficiency is probably common.