Boy I wish this study had been done when I was still nursing my kids. It seems that women who consumed large amounts of caffeine (>300 mg/day), about the equivalent of 16 ounces of Starbucks Pikes Place Brew, six cans of Diet Coke, or three 16-ounce cups of McDonald’s brewed coffee, had babies who slept just as well as moms who consumed no caffeine.
The women in the study had large amounts of caffeine regularly through the end of the pregnancy through the third month after birth when the study was done. This consistent consumption could have resulted in the infant adjusting to the caffeine exposure just like we do and that may account for the lack of differences between the caffeinated infants and the non-caffeinated ones.
I guess women who enjoy their caffeine should be heartened by the news but remember that infants may experience withdrawal symptoms like fatigue and headache if you suddenly change your consumption patterns or stop breastfeeding abruptly. By weaning slowly from nursing you can minimize the chance of withdrawal. And women who have gone without caffeine and start back up may see a period of transition in which the infant is more wakeful and agitated as he adjusts to your caffeine intake.
All in all though caffeine isn’t harmful for mother or infant but transitions when you start or stop may be accompanied by a day or two of adjustment symptoms.
Bottom line: if you want your cup of coffee while pregnant or nursing have it but remain consistent to minimize symptoms for your infant.