Another highlight from the ALCA Conference in Hobart was a paper
presented by Jacqueline Kent, who works with Peter Hartmann at the
University of WA. They are using the "Computerised Breast
Measurement System" to measure morphological changes in breast size
during pregnancy and up to 6 months of lactation. They have also
collected blood samples to measure  human placental lactogen (HPL)
and prolactin, and 24-h urine samples for measurement of lactose, and
metabolites of oestrogen and progesterone. During lactation they
measured 24-h milk production.

She showed how the pattern of change in breast size during pregnancy
was variable in amount (12ml to 368ml)  and timing (mostly late first
trimester, but not always). Breast growth was statistically related
to the concentration of HPL in plasma, rather than prolactin or the
excretion of metabolites of oestrogen or progesterone. All mothers
showed an increase in the excretion of lactose in the urine during
the second  trimester of pregnancy, indicating the development at
that time of the capacity of the breasts to synthesise lactose. The
rate of excretion of lactose (in pregnancy) was positively  related
to the concentration of prolactin in the plasma.

Despite the variation in breast growth during pregnancy, all mothers
breastfed successfully.  Milk production  ranged from 459ml/day to
1370ml/day at 1 month of lactation, and 832ml/day to 1210ml/day at 6
months. One woman had almost no changes during pregnancy, but her
(empty) breast size increased during the first few weeks after
delivery (she breastfed with no problems).  They suggest that lack of
breast development in pregnancy is not always a problem. Also, it
appears that the breast can still develop after delivery. They will
continue to measure the  breast volume and milk production of these
mothers until 3 months after weaning. Please note that the study is
not yet complete or published.


Ros Escott
[log in to unmask]