While full nursing (no supplemental bottles or solid foods) with co-sleeping can suppress ovulation, some women will continue to ovulate even during nursing, so yes, a woman who is nursing can definitely become pregnant.

Every shift away from full nursing with co-sleeping increases the chances that a woman will ovulate during the time she is nursing... so moving the baby to hir own bed; going back to work and pumping (even if baby is only getting breast milk); adding solid foods (even without full weaning); or supplementing with bottles/formula/etc. can all allow enough hormone shift that the reproductive system kicks back into gear.

It is also important to remember that a woman will ovulate 2 weeks BEFORE her first post-birth menstruation -- so it's possible to get pregnant again before ever having a period to warn her that she's fertile again.

Of my clients who maintained ovulation suppression past their 12th post-partum week, the ones who maintained amenorrhea longest naturally (without birth control) tended to have the following characteristics:

• Within a healthy/normal weight range
• Consistent "family bed/co-sleeping" with infant
• 100% nursing, on demand
• Worked at/from home, or were able to take baby to work and nurse on demand throughout the day
• Able to manage stress well.

While breastfeeding decreases overall fertility, as far as I am aware, it does not explain the relatively low brithrate of hunter-gatherers, who tended to space children at around 3-4 years. (The number I have read for the number of months exclusive breastfeeding + ammenorhea can relatively reliably be counted on for birth control is 6 months) Infantacide was likely used for children born too close together. http://www.alanmacfarlane.com/savage/A-FETICI.PDF

Yes, definitely!

Lactational ammenorrhea may delay ovulation for 9-18 months (more or less), especially when co-sleeping, but as the child starts eating solid food and stops nursing as often, ovulation generally resumes.

For some women, nursing on demand and co-sleeping are still not enough to stop ovulation/pregnancy.

IIRC, those particular H/G cultures also practiced avoidance of intercourse (though not sex!) until the child self-weans in order to keep the population down. Also helpful for mom to have the time to replenish her nutrient stores for the next child.

We've done it. Not as a "planned" method, but as a "nice side effect".

Our kids are all 2-3 years apart and we practiced no birth control (not even rhythm) since the conception of the first child, 17 years ago.

We have six kids: 16, 14, 11, 8, 6, 4 and wife is pregnant with #7 (due September).

She had 0-2 periods (usually only one) between each kid.

Yep, I didn't get a period between my two children until I weaned my first child at 22 months. I believe a few factors are involved: frequency of nursing and body fat are the two biggest ones, iirc. Just anecdotally, I can tell you that I was quite thin at that time (though I don't think thin enough to explain period absence on its own), and among my friends who were also nursing, my friends who were thinner tended to not get periods back, and those who were heavier tended to get periods back

My mother(who had 12 children!) got pregnant again very quickly, multiple times, even while breast feeding 100%. I have a brother only 14 months younger, and I also have two siblings who are only 13 months apart.

My sister also breast fed 100%, and she was hopeful that breast feeding would serve as a birth control method as well. She became pregnant three months after giving birth, and so my nephew and neice are only 12 months apart.

I haven't had a period since December 2009. Even though my 19 month old eats tons of other foods I nurse on demand at home and she sleeps with me. We never used nipple shields and only used pacifiers for a short period of time as well. I am surprised it has lasted this long; I am in nursing school and have 12 hour shifts so I'm curious as to why I have lactational amenorrhea while some exusively breastfeeding mothers get their periods back within a couple months.

This can go both ways. I've known women who get pregnant within the first 4 months after having a baby, even in optimal situations (exclusively breastfeeding, co-sleeping). On the other hand, my cycle did not return until my son was 17 months old and was HIGHLY irregular until he weaned (i.e. 50-60 day cycles). At that point he was really only nursing once or twice a day and no longer at night. So, if I count back I ovulated probably 3, maybe 4 times in the first two years of his life? It would have been really unlikely if I'd managed to become pregnant.

The lactational amenorrhea method of birth control works statistically speaking, most women will not get pregnant within the first 6 months after having a baby if they are exclusively breast feeding. It will not work for other women. And still others of us will have LOOOOONG extended stretches of interrupted fertility while nursing. Among a population as a whole however, exclusive breast feeding will tend to extend the spacing between babies.

I believe this worked for hunter-gatherers because they probably had their babies skin-to-skin almost 24/7. Today, it is said that "ecological" breastfeeding (using exclusively the breast for food, comfort, etc.-- no pacifiers, no bottles, and wearing your baby in a sling constantly, and co-sleeping), will result in suppressed fertility for at least one year. Americans tend to be more distal, using pacifiers, placing babies in bouncy seats, using bottles (even if it is breastmilk), etc. So it's not enough just to ask if breastfeeding in general will suppress fertility. You have to know what kind of breastfeeding you're doing.

I have a 12-week old and my cycle started coming back 6 weeks ago. I exclusively breastfeed, but I was using pumped bottles for several weeks, during which time my cycle returned (not sure if that is WHY my fertility wasn't suppressed, though). I also use pacifiers and although I use a sling often, I also use a stroller as well. I am quite certain that my fertility hasn't returned, however, because I use Natural Family Planning and know when I am having a fertile period each month. So far, my pre-pregnancy fertility signs have not returned, even though my cycle seems to be coming back (I say "seems" because I haven't had a regular, heavy period yet).

My advice to you would be to learn how to detect your own fertility. This is relatively simple. There are several methods. The great thing about this is that you do not need to use a barrier method or take hormonal contraceptives in order to naturally space out your children. While breastfeeding is a great way to suppress fertility, the only way to be sure that you are spacing your children is to abstain from sex during several days every month when you are ovulating (and it is very simple to learn when you are ovulating). Personally I observe cervical mucous and supplement with a fertility monitor, so I knew exactly what was happening pre-preg. Just Google "NFP"-- I like the Billings Method of NFP, but there are other excellent methods as well. And they are 98% effective. They can also be used to help achieve pregnancy for women who have tricky cycles or disorders such as PCOS.

I have 4 kids all spaced almost exactly 2 years apart (3birthdays in first 2 weeks of may!) I didnt have a period from time of conception of baby #1 until month after last feed of baby#4 I conceived #2 and the rest during first fertile window after last feed. THese were all post 12mths old... I co slept and I worked full time away from babies, two were supplementary fed (dad reckoned they needed it not me!) consequently they were very heavy babies as opposed to the regular chubsters....