From the BFAB p 407: "As of this writing, there are no medical studies that have examined the effect of breastfeeding during pregnancy on pregnancy outcomes."
The studies I mentioned above (there are only two: one covers both things I mentioned) are:
- J Hum Lact. 1993 Jun;9(2):83-8.
Breastfeeding during pregnancy.Moscone SR, Moore MJ.
Abstract here:
http://www.ncbi.nlm.nih.gov/pubmed/8251083
- American Journal of Clinical Nutrition, Vol 52, 280-288, 1990
Maternal and fetal responses to the stresses of lactation concurrent with pregnancy and of short recuperative intervals K Merchant, R Martorell and J Haas
Abstract here:
http://www.ajcn.org/cgi/content/abstract/52/2/280