Oestrogen stimulated neurophysin in pregnancy and lactation

Serum concentrations of oestrogen stimulated neurophysin (ESN) were measured throughout pregnancy in thirty-one women and until 6 weeks post-partum in a further twenty-three. During pregnancy ESN rose progressively and values during labour were similar to those immediately before delivery. There were significant correlations (P less than 0.05) between serum ESN and oestradiol values measured in samples from four patients. After delivery the concentration of ESN fell rapidly to the range for non-pregnant women by 5 days post-partum, whether the mothers lactated or not, and remained fairly constant for the next 6 weeks. Bromocriptine or metoclopramide, drugs which affect prolactin secretion, were without effect on ESN values. At 8 days post-partum in sixteen of the eighteen patients studied there was an increase in ESN concentration 30 min after suckling commenced. At 6 weeks similar changes occurred in five of the ten subjects studied. In contrast, at 8 days there was no significant change in ESN in four mothers who bottle fed their babies over the 90 min studied. The relationship between ESN and hormonal changes during pregnancy and lactation is discussed in the light of these results.