Hi, my name is Medora and I am a junior nursing student at the University of 
North Dakota.  I am in my second semester of childbearing classes and am 
working in the OB setting for clinicals.  I have been following the discussions 
on Lactnet for a few weeks and I was interested by a post on Polycystic 
Ovary Syndrome (PCOS) and difficulty breastfeeding.  
An article by Marasco, Marmet, and Shell wrote an article on the relationship 
between PCOS and its possible connection to inadequate milk supply.  This 
study focused on two of the diagnostic criteria of PCOS: hyperandrogenemia 
and chronic anovulation.  The presence of elevated levels of androgens may 
present problems to the process of lactation; they may down regulate the 
effect of estrogen and prolactin receptors.  Obesity in women with PCOS may 
also contribute to the elevated levels of estrogen.  PCOS onset occurs most 
often during puberty thus creating potential for disruption of mammary 
development of the ductile system, in which estrogen plays a large role, and 
lobuloalveolar development, which progesterone regulates.  Prolactin is 
important for mammary development during pregnancy and the endocrine 
phase of lactation can be limited if prolactin receptors are down regulated 
(2000, p.143-4, 6-7).  
Another key hormone in breastfeeding is insulin.  Insulin plays a role in 
stimulating stem cells of the mammary glands to grow and divide during the 
beginning of milk synthesis.  Insulin resistance is a common problem in women 
with PCOS and therefore a potential deterrent to effective lactogenesis 
(Marasco et al., p. 147).  
A common treatment for insulin resistance in women with PCOS is metformin.  
This drug has been shown in many studies to be very effective for women 
with PCOS who have infertility problems by facilitating a more regular ovulation 
and conception.  Metformin also can decrease miscarriage, gestational 
diabetes, macrosomia, and is not teratogenic (Glueck et al., p. 628).  
However, less studied is the effect of metformin on breastfeeding and infants.  
I found several recent studies examining the presence of metformin in human 
breast milk and its effects on the health, growth and development on the 
breastfeeding infant.  
Metformin, a biguanide, improves glucose tolerance by reducing hepatic 
glucose production rather than stimulating insulin release, which can then 
increase insulin-stimulated glucose intake by the cells.  This drug was also 
found not to increase plasma glucose concentrations or cause hypoglycemia in 
healthy adults, and the same was also found to be true in infants (Hale et al., 
p. 1512 & Briggs et al., p.1440).  Hale et al. and Briggs et al. both concluded 
that the amount of drug found in the mother’s breast milk stayed fairly 
constant over a 12 hour period and that the concentration of drug in the milk 
was below 10% of the mother’s weight-adjusted dose (mg/kg/d), a level that 
is considered to be not clinically concerning (Hale et al., p. 1512-3 & Briggs et 
al., p.1440).  Both Hale et al. and Briggs et al. concluded that women taking 
metformin postpartum should still be encouraged to breastfeed as no adverse 
affects were attributable to the infants (Hale et al., p. 1513 & Briggs et al., 
p.1440).  
A study performed by Glueck et al. showed that formula-fed infants who were 
born to women taking metformin during pregnancy were just as healthy as 
breastfed infants born to women taking metformin during pregnancy.  At three 
and six month check-ups, children of both groups were at the same level of 
weight, height and motor-social development for their age.  Glueck et al. also 
conclude that metformin appears to be safe and effective for lactating 
mothers and their infants (p.628, 631).  
	This is what I had found in the literature, but I was wondering if 
anyone had seen metformin used successfully to help mothers with PCOS to 
lactate more successfully?


References:

Briggs, G. G., Ambrose, P. J., Nageotte, M. P., Padilla, G., & Wan, S. (2005). 
Excretion of Metformin Into Breast Milk and the Effect on Nursing Infants. 
American College of Obstetricians and Gynecologists. 105(6): 1437-41

Gluec, C. J., Salehi, M., Sieve, L., & Wang, P. (2006). Growth, Motor, and 
Social Development in Breast- and Formula- Fed Infants of Metformin-Treated 
Women with Polycystic Ovary Syndrome. Journal of Pediatrics. 148: 628-32.

Hale, T. W., Kristensen, J. H., Hackett, J. P., Kohan, R., & Ilett, K. F. (2002). 
Transfer of Metformin Into Human Milk. Diabetologia. 45: 1509-14.

Marasco, L., Marmet, C., & Shell, E. (2000). Polycystic Ovary Syndrome: A 
Connection to Insufficient Milk Supply? Journal of Human Lactation. 16(2): 143-
8.

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