Cord haemoglobin in low birthweight infants.

Cord haemoglobin was measured in 349 low birthweight infants born after a pregnancy lasting 28 to 41 weeks inclusive. 82 babies were small-for-dates and were born after 36 weeks' gestation; their Hb was not related to sex or duration of pregnancy, but there was a negative correlation with placental weight and placental weight/birthweight ratios. The mean Hb of small-for-dates babies (17·09±2·11 g/100 ml) was higher than for comparable normal babies (16·24±2·26 g/100 ml). In normal-for-dates females there was a linear relation between Hb and duration of pregnancy approximately expressed by: cord Hb (g/100 ml) = 7 + gestational age in lunar months. In males a plateau Hb of 16·22 g/100 ml was reached at 32 weeks.