Predictors of Lactogenesis II

Lactogenesis I occurs during pregnancy (midpregnancy and beyond), when the mammary glands
becomes sufficiently differentiated to secrete small quantities of specific milk components.
Lactogenesis II is defined as the onset of plentiful milk secretion and typically occurs
between 30-40 hours post delivery. It is typically described by women as a sense of fullness
and leakage of milk which is subjectively reported between 50-73 hours post delivery. The
incidence of delayed lactogenesis II ranges from 17-44%.

The risk of neonatal weight loss is up to 7 times greater for exclusively breastfed infants
of women who experience delayed lactogenesis II as compared to women who experience typical
onset lactogenesisII. In a qualitative study of 114 lactating women, increasing BMI was
significantly associated with maternal perceptions of delayed onset of lactogenesis II.

The United States Breastfeeding Committee supports exclusive breastfeeding for the first 6
months of life because it "may exert a small but positive influence in reducing the risk of
obesity in childhood and later in life…" Breastfeeding has also been associated with
decreased risk of maternal morbidities such as type 2 diabetes, subclinical cardiovascular
disease and less abdominal visceral adiposity. Given that prolonged breastfeeding improves
the overall health of the mother infant dyad, it is critical to obtain a better understanding
of those factors predictive of successful breastfeeding outcomes.

At University of South Florida our clinics serve an ethnically diverse population which would
benefit from directed efforts at improving breastfeeding. Before we can undertake such a plan
we need to assess the contemporary factors impacting lactogenesis.

We plan to prospectively enroll 186 pregnant women into a protocol to examine factors
associated with delayed lactogenesis. Ninety-three women will have a BMI of 30 or higher at
the time of delivery and the other 93 women will have a BMI ≤ 29 at the time of delivery.

Inclusion Criteria:

- intend to attempt breastfeeding

- Expecting a live-born infant

- Singleton pregnancy

- English or Spanish language fluency

- Delivered at fullterm gestation

Exclusion Criteria:

- Multiple gestation delivery

- Delivered pre-term (<36weeks and 6 days of gestation)

- Not admitted to Mother Baby Unit (MBU) (ie admitted to intensive or special care unit
or to Labor & Delivery Unit for postpartum monitoring)

- Mother did not initiate breastfeeding within 12 hours.

- No telephone access

- History of breast reduction or enlargement surgery

- Planning to formula feed from birth (no intention to breastfeed or try breastfeeding).