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Body Literacy: Breastfeeding + Fertility

Updated: Sep 14, 2019

My theme song for the breastfeeding season of fertility is from none other than Gwen Stefani. (Warning: language.)

As if the saggy stomach, milk leakage, and totally dependent tiny human weren’t enough for a postpartum mom to worry about, breastfeeding throws a fertility curveball.

I tell my clients, “the only thing predictable about the postpartum transition is that it isn’t unpredictable.” It’s a bit tongue-in-cheek, especially since I teach a model of NFP with postpartum-specific protocols, but there is an element of truth. Even with the most specific protocol to follow, fertility seems to hold a wild card while breastfeeding.

Why is this?

Some cruel joke of Mother Nature as a participation ribbon for completing pregnancy? Not exactly. The body goes through intense changes during pregnancy. Progesterone is at its highest level ever in a woman’s life, then plummets with the delivery of the placenta.

These are the crazy high levels of hormones in pregnancy:

A woman does not have menstrual cycles for the duration of the pregnancy. Suddenly, with breastfeeding, hormones like oxytocin and prolactin start making a regular appearance, which was not the case pre-pregnancy.

Physiological triggers from breastfeeding (specifically, the baby suckling at the breast) send stimuli to the brain. The fertility-inducing hormones produced by the pituitary gland are suppressed as a breastfeeding-specific hormone (prolactin) is released.

Since there are no fertility pituitary hormones (such as FSH) to stimulate the maturation of a follicle and LH to stimulate ovulation, fertility remains suppressed.

Breastfeeding alone can be 98% effective if:

• Baby is less than 6 months old

• Baby is exclusively breastfed (baby suckling at the breast often is key)

• Menstruation has not returned

• Baby nurses at least every 4 hours during the day and every 6 hours at night.

ALL of the above criteria must be present for breastfeeding alone/LAM (lactation amenorrhea method) to be 98% effective. At 6 months, unless another criteria changes first, LAM is no longer considered optimally effective.

Typically, around 6 months, table food is introduced, babies (who are not my children) sleep longer, and there is a wider stretch between breastfeeding sessions. When more time passes between baby nursing at the breast, there is less frequent stimulation of prolactin so the fertility hormones (FSH, estrogen) have room to rise again.

Unfortunately, babies rarely space out nursing sessions in a linear fashion. She may sleep 8 hours straight at night for 2 weeks, and then she cuts teeth. Or catches a virus. And now she’s nursing every 3 hours again.

Signs of fertility begin to show up, and then they disappear again. Estrogen causes production of cervical mucus. If estrogen is beginning to rise (in response to a baby who sleeps all night) but then gets suppressed again as baby decides to nurse like a newborn the next week, the effect on mucus production leads to confusing observations. Many women experience either constant mucus production or zero mucus production in the postpartum season. This is a direct result of the variability of estrogen as it responds to changes in breastfeeding.

Well, it was totally crazy for a while, but I got my first postpartum period! So things are back to normal and predictable, right?

I thought so. And then I had no idea how I conceived on day 29 in my second postpartum cycle. 29 days was my previous cycle length! Not my ovulation day!

There’s a 6(ish) cycle transition once postpartum cycles return, if the mother is breastfeeding.

Characteristics of this transition are:

1. VERY delayed ovulation (think: days 26-40) that moves a little earlier each cycle until it settles back in to a woman’s normal cycle pattern.

2. SUPER short post peak (luteal) phase that lengthens a little with each cycle until it reaches the healthy approximately 12-14 day length.

Here an example of a postpartum transition based on the 100+ breastfeeding moms I've worked with:

Cycle 1: 38 days (Peak: Day 32)

Cycle 2: 36 days (Peak: Day 30)

Cycle 3: 36 days (Peak: Day 28)

Cycle 4: 35 days (Peak: Day 25)

Cycle 5: 34 days (Peak: Day 21)

Cycle 6: 31 days (Peak: Day 19)

Cycle 7: 30 days (Peak: Day 17)

Note: These post-peak phases look (and are) very short! But they’re also part of an expected and anticipated transition. Most women transition through and back to regular cycles with healthy luteal phases.

NO ONE told me this after my first son. I thought, “Fertile signs around day 15. Sweet, that’s normal for me! Day 25 rolls around, yeah we are good to go!” Then BAM! Day 29 ovulation.

Now I understand this is TEXTBOOK for the early postpartum transition.

Finally, after about 6 postpartum cycles, things should be settling back in to a semi—predictable pattern.

This post is not intended, nor is it sufficient, to substitute for working with a qualified NFP instructor. Some women have an pretty “normal” peak day with a 12-14 day luteal phase in their first postpartum cycle— and working with an instructor will help you navigate wherever you fall on the postpartum spectrum. Of any NFP season, breastfeeding may be the most important one to work with an instructor if you are trying to avoid pregnancy.

I have quickly learned how many women (myself included) have no clue what to make of postpartum fertility signs. Many women assume they are confused because of sleep deprivation or lack of attention paid to fertility markers when holding a baby and peeing at the same time. (Don’t act surprised. You know you’ve done it, too.) You aren’t crazy. Or incapable of understanding your fertility.

Postpartum breastfeeding fertility is a new ballgame. Still totally manageable with NFP, just with some new rules and a gameplan specific to postpartum fertility.

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