Db. Cox et al., Breast growth and the urinary excretion of lactose during human pregnancy and early lactation: Endocrine relationships, EXP PHYSIOL, 84(2), 1999, pp. 421-434
Breast volume and morphology of eight subjects were measured before concept
ion and at intervals throughout pregnancy until 1 month of lactation. Breas
t volume before conception ranged from 293 to 964 ml. At the end of pregnan
cy the volume of breast tissue had increased by 145 +/- 19 ml (mean +/- S.E
.M., n = 13 breasts, range 12-227 ml) with a further increase to 211 +/- 16
ml (n = 12 breasts, range 129-320 ml) by 1 month of lactation. Urinary exc
retion of lactose increased at 22 weeks of pregnancy, signalling the capaci
ty of the breast to synthesize lactose at this time During pregnancy, both
the change in breast volume and the change in cross-sectional area of the a
reola were related to the concentration of human placental lactogen in the
plasma. The growth of the nipple and the rate of excretion of lactose were
related to the concentration of prolactin in the plasma. During the first 3
days after birth, the rate of excretion of lactose was related to the rate
of excretion of progesterone. There was no relationship between the growth
of the breast during pregnancy and the amount of milk produced at 1 month
of lactation.