PREGNANCY AND BREAST PART 2

mothers with very low milk supply, breast hypoplasia
(too little glandular tissue), or hyperplasia (overgrowth of
glandular tissue). With rising rates of obesity, there is
some concern about the effect of obesity on lactation,
particularly with increasing reports that obese women are
experiencing breastfeeding difficulties (see review by
Jevitt et al. on page 606). Only a few studies have been
carried out to investigate the effect of obesity on lacta-
tion, and they have been difficult to perform because of
known confounding factors such as the mode of delivery
and parity. These studies show that pregnant women with
a high body mass index are more likely to experience
delayed lactogenesis II.
44
While the cause of delayed
lactation is not clear, hormonal influences on milk
production, increased difficulty attaining a successful
infant latch to the breast, and socio-cultural factors have
been suggested.
45
Knowledge of the normal features of the ductal system
is integral to diagnosing ductal abnormalities such as
galactoceles and blocked ducts. A palpable lump and
ultrasonic features of non-compressible ducts is indica-
tive of a blocked duct and should not be considered
“normal” for the lactating breast. Furthermore, the ultra-
sound scan may identify the level of the blockage,
providing useful information for treatment with thera-
peutic ultrasound.
Mothers of premature and sick infants rely on breast
pumps to initiate and maintain lactation. Clinically, it has
been observed that larger shield sizes may optimize milk
removal for some mothers. It is therefore feasible that
compression of superficial ducts within the breast by the
shield may indeed compromise milk flow. Further re-
search is required to determine the effect of ductal
anatomy on pumping performance in women.
Many women who have breast reduction surgery may
be able to partially breastfeed their infant, but relatively
few are able to exclusively breastfeed.
52
This is likely
because of the codistribution of glandular and fatty tissue
within both the lactating
38
and non-lactating breast,
53
making it difficult to preferentially remove fatty tissue. In
addition, milk outflow is probably disrupted, because
there are fewer numbers of ducts than previously
thought.
21,38
Furthermore, it is possible that the milk
ejection reflex may be inhibited if the nerve supply to the
nipple is disturbed.
The absence of lactiferous sinuses or milk reservoirs
leads one to reconsider the mechanism by which the
infant removes milk from the breast. Generally, it is
believed that the predominant action involved in remov-
ing milk from the breast is peristalsis or a stripping
action.
54
We have found that milk flows into the infant’s
mouth when its tongue is lowered and vacuum is applied
to the breast. This finding suggests that the vacuum
applied by the breastfeeding infant is a major component
of milk removal.
55
Indeed, it is evident that correct
positioning and attachment of the infant to the breast is
IMportant for successful breastfeeding; however, the
mechanism should be fully understood in order to diag-
nose and manage infants with sucking abnormalities.
Finally, the absence of the lactiferous sinuses further
emphasises the critical nature of milk ejection for suc-
cessful breastfeeding, because only small amounts of
milk are available before the stimulation of milk ejecTION