How Your Menstrual Cycle Can Affect Your Baby’s Sleep

How Your Menstrual Cycle Can Affect Your Baby’s Sleep

Let’s talk about a topic you probably thought you’d never come across here at the Baby Sleep Site… Let’s talk about menstrual cycles!

Now don’t feel awkward. We’re not going into detail here! Instead, we’re going to take a look at how your menstrual cycle may impact your baby’s sleep. You wouldn’t imagine there would be a connection, would you?

Turns out there is!

Your Menstrual Cycle Can Affect Your Breastmilk

Many of you already know (from first-hand experience or otherwise) that nursing a baby delays the return of a woman’s period after she gives birth. For some women, the delay is a matter of weeks; for others, their period is delayed the entire time they nurse (even if they nurse for years!).

Most of us fall somewhere in the middle of that spectrum. It’s typical for a woman’s period to be delayed when her baby is young and is nursing frequently and regularly. Then, as her baby begins eating solid food and nursing less, her period gradually returns.

Here’s what’s interesting: once your period returns, it can have a big impact on your “nursing rhythm”. We can chalk this up to hormones; a few days before our periods start, our blood calcium levels drop. This drop in blood calcium can cause two things to happen:

  • It can cause a drop in milk supply. This doesn’t happen for every woman, but some women notice that starting a few days before their periods, their milk supply drops a bit. This lasts until a few days after the period has started.
  • It can slightly change the flavor of your milk. Again, this isn’t true for everyone. But menstruation can slightly alter your milk’s taste, making it less palatable for your baby. This alteration starts a few days before your period and lasts until a few days after your period has begun.

The result? If your milk supply is low, you can expect your baby to nurse more frequently. And if your breastmilk tastes “off” to your baby, you might find that she drinks less than usual and doesn’t nurse as eagerly. For a rare few, there may appear to be a sudden nursing strike, but should be temporary.

Nicole’s Note:
“I was extremely fortunate that my period didn’t return until I weaned my eldest son right around a year old. It didn’t return even when we night-weaned! I do work with some families, though, who see a noticeable drop in milk supply once they night-wean and around their menstrual cycle every month. It can be extremely stressful for mom, which doesn’t help!”

Your Menstrual Cycle Can Affect Your Baby’s Sleep

The logical conclusion of all the information above is pretty simple — if you aren’t making as much breastmilk as you normally do, or if your baby isn’t drinking much because it tastes different, then it’s likely that your baby make feel hungrier than usual. And hunger is often bad for sleep.

You might find that starting a few days before your period, your baby begins waking more frequently at night, demanding a feeding. Or you might find that naps are shorter than usual because hunger is waking your baby.

Of course, this is assuming your baby was sleeping fairly well to begin with; if your baby has never slept through the night, or is a chronically bad napper, or has a dozen different sleep associations, then you might not notice a difference (in a bad way)!

What If You’re Formula Feeding?

Naturally, moms who formula feed won’t feel the same effects from their menstrual cycles as breastfeeding moms. But that doesn’t mean that formula-feeding moms are exempt from menstrual symptoms, does it? PMS doesn’t play favorites, after all — mood swings, cramps, bloating, and fatigue affect most women, regardless of whether they’re breastfeeding.

If you’re a formula-feeding mom who has an especially sensitive baby, you may notice that when your PMS symptoms set in, your baby becomes crankier and more restless. Her sleep may even be disrupted. This happens because babies (especially sensitive ones) tend to pick up on their parents’ moods and stress levels. So if your PMS is sending your stress level soaring, or if it’s making you extremely irritable and cranky, it’s likely your baby’s going to notice.

Preventing Your Menstrual Cycle From Affecting Your Baby’s Sleep

This news isn’t especially great, especially if you’re already struggling with sleep. You can’t exactly prevent your period. But there are steps you can take to make your menstrual cycles have less of an effect on your baby’s sleep.

Specifically, you can take a combination calcium/magnesium supplement. Remember how I mentioned that it’s the drop in blood calcium levels that causes the low milk supply, and the altered taste to your breastmilk? Well, if you start taking a calcium/magnesium supplement a few days before your period starts, you may be able to prevent those complications.

Good news for formula-feeding moms, too — calcium and magnesium are two minerals that have been shown to naturally alleviate some common PMS symptoms, like fatigue and appetite changes. So a calcium/magnesium supplement can help you as well.

Why a calcium/magnesium supplement, and not just a calcium pill? Magnesium helps your body absorb calcium; without the magnesium, your body would only absorb a fraction of the supplement’s total calcium.

We’re not going to give specific dosages here; that’s something you should talk to your doctor about. But for more information on how a calcium/magnesium supplement can help (and for additional information about how your menstrual cycle affects your breastmilk), check out this article, on The La Leche League website.


Hartmann, P.E. & Prosser, C.G. (1982) Acute changes in the composition of milk during the ovulatory menstrual cycle in lactating women. Journal of Physiology (London), 324, 21-30. 29,237-246.

Nagvi, H.M., Baseer A., (2001). Milk Composition Changes – a Simple and non-invasive Method of detecting Ovulation in Lactating Women. Journal of Pakistan Medical Association. Electronic Access:

Prentice, A.M. et. al. (1984). The effects of water abstention of milk synthesis in lactating women. Clinical Sciences, 66: 291-298

Prosser CG, Hartmann PE.(1983). Saliva and breast milk composition during the menstrual cycle of women. The Australian journal of experimental biology and medical science, 61 (pt 3):265-75

Does your menstrual cycle affect your baby’s sleep?

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