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  • Writer's pictureLiz Madsen, FCP, FNTP

Postpartum Fertility - The 56 Day Instruction

Updated: Feb 20, 2021

Did you know after the birth of a baby, if the mom is totally breastfeeding, meaning nothing is going in baby's mouth except the breast on demand, the first 56 days are considered infertile? She will not ovulate or become pregnant in that time frame.

Does it sound fishy that the first 8 weeks postpartum are infertile? I would be skeptical too, if I didn't know the facts. I will present the facts behind the 56 day rule, which does not apply to everyone, and you can decide for yourself if you would trust it.

Disclaimer: I am not a doctor, I can not give you nor do I intend to give medical advice. If you use Creighton Model and are not my client, contact your practitioner for more information. If you use another form of Natural Family Planning or Fertility Awareness, contact your instructor for more information.


Prolactin is the hormone produced by the anterior pituitary gland in the brain. It's production is stimulated by the delivery of the placenta after birth to initiate lactation. Once milk is produced and the baby starts suckling, then prolactin production is based on how often the infant nurses at the breast. (Reproductive Anatomy and Physiology, Hilgers, 2004)

The Power of a suckling baby

The action of breastfeeding reduces production of hormones and suppresses ovulation, which is pretty widely known. There is a method of natural family planning based solely on this fact, lactation amenorrhea method or LAM. Prolactin itself is not responsible for the suppression of ovulation, but rather the suckling of the baby on the breast which suppresses the hormones that initiate ovulation, and also stimulate the production of prolactin. Check out this study on LAM. Woah, baby.

Cool, but why 56 days?

A researcher named Cronin did a study in 1968 that revealed that ovulation in a lactating woman prior to 10 weeks postpartum was a rare event. 10 weeks is 70 days. #lizthemathmatician. He found that there was a 1 in 20 chance of ovulation happening prior to the first menstrual period and prior to 42 days postpartum. There was another study in 1982 where they compared bottle feeding mothers to breastfeeding mothers' return of ovulation. Breastfeeding mothers average return of ovulation was just over 36 weeks, that's about 9 months postpartum. The bottle-feeding moms average return of ovulation was at 10 weeks postpartum. Read more on that here. Both studies are consistent with one another in that ovulation in their test subjects did not happen before the 70 day mark. 56 days is designated by Creighton Model FertilityCare™ System as, I assume, a conservative number, 2 weeks before that 10 week cut off, where couples who are totally breastfeeding can feel confident that their return of fertility will happen after the 56-day mark.

Is Everyone Infertile for 56 days Postpartum?

This does not apply to everyone. Mom has to be breastfeeding. The baby can not be given anything but the breast to suck on (remember the power of a suckling baby?) so not even a binky. The baby can not eat anything other than breastmilk or a little water. So if your baby was given formula or sugar water at the hospital or took donor milk, they would not be considered "totally breastfeeding." Also, pumping is not considered totally breastfeeding. The mechanism of the pump is not the same as the baby's mechanism of suckling. The reasons behind this are that if the baby stops consuming moms milk directly from the breast at any point, milk production can reduce, even slightly, and change the mom's ability to make hormones that stimulate ovulation. As in, she could ovulate.

It is a very selective group of moms that can fit into this category of totally breastfeeding. If totally breastfeeding works, that's beautiful; If it doesn't work, that is more than ok. Read on.

Word of caution

This type of on demand feeding is tough on moms and even dads! It can drain moms physically and emotionally especially if they aren't getting any sleep and can drain dads who are trying to fill in everywhere mom can't be. I'm just being real. The definition of "totally breastfeeding" is hard for most parents to live up to. Don't get me wrong, I encourage breastfeeding. I breastfed all of my boys for a long time, one of them up to his 2nd birthday. I only "totally" breastfed one of them in those first 56 days, and it was because he refused the binky - to my great dismay! If you read my post on PPD, you'll see I didn't have my life totally together in that time frame. It was a trade off. As parents, most things in life are like that. You give up one thing for another. My experience will not be everyone's but many moms and dads suffer this exhaustion even if they don't talk about it or acknowledge it themselves.

Enter: not relying on the 56 day rule.

56 Day Rule is not for everyone - and that's great!

You know what is really liberating for the mom who just had a baby and is motivated to avoid pregnancy until she's good and ready, and does not fall under the definition of totally breastfeeding: not having to follow the 56-day instruction. Yes, some parents have it made in the shade with their total breastfeeding dreams realized (and maybe their sleep and sanity waning). We don't need to be jealous of them, though, because there is still an easy way to monitor your fertility: charting! Yes, with Creighton Model FertilityCare™ System, you can navigate your return of fertility just fine. Charting postpartum is the same as before becoming pregnant, with some adjusted instructions, but in practice it is the same.

Great info, where do I go from here?

If you are my client, contact me for more info on when to resume charting after your baby is born. If you want to look into Creighton Model for postpartum charting, contact me and I can help get you started. Other forms of Fertility Awareness and Natural Family Planning have their own postpartum guidelines, so please contact your instructor for those instructions.

Now you have the facts, would you trust the 56 day rule?

It's your fertility, it's up to you!

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