At 42, I was deep in perimenopause (hot flashes, night sweats, insomnia, etc.) when I decided to transfer a frozen embryo. I was lucky enough to get pregnant, and if all goes according to plan, I’ll deliver my second baby when I’m 43. If I hadn’t gotten pregnant, I would’ve pursued HRT for my peri symptoms, and now I’m petrified of a hormonal crash-and-burn postpartum. I haven’t been able to find any good data on HRT and breastfeeding, and am generally concerned about what might happen after birth. I’d be so grateful for any guidance!
—Jackie
First things first: congratulations! Certainly women have had babies in their 40s in the past — my mother’s generation called them “change-of-life” babies, presumably because they were conceived by accident when a woman’s periods were irregular. But reproductive technology is helping women conceive during the perimenopausal years more often these days.
There is no published medical literature regarding the postpartum hormonal changes of women who get pregnant in perimenopause. But if we consider the physiology of the postpartum period, we can get a pretty good sense of what to expect.
During pregnancy, estrogen and progesterone levels are many times higher than those seen in women during their peak reproductive years who are not pregnant. Let’s use some numbers to get context. Estrogen levels at the end of pregnancy range from about 3,000 to 6,000 nanograms per milliliter (ng/ml). In a non-pregnant woman in her peak reproductive years, estrogen levels range from 30 ng/ml at the beginning of a menstrual cycle to roughly 300 ng/ml when they peak around ovulation. Estrogen levels in perimenopausal women can be hugely variable, from virtually 0 to 700 ng/ml and everywhere in between.
It is volatility in estrogen levels that often triggers symptoms. All women’s estrogen levels drop at least a hundredfold in the six weeks after pregnancy, whether they were in their peak reproductive years or in perimenopause. This is why many women experience hot flushes and night sweats during the immediate postpartum period. During breastfeeding, the hormones that promote breastfeeding keep estrogen levels low, often for many months.
Typically, during breastfeeding we avoid giving women estrogen because it can affect milk supply, but progesterone in the form of a progesterone-only birth control pill or progestin-eluting IUD are great options for contraception (just because you were perimenopausal before pregnancy does not mean you cannot get pregnant!).
Once you are done breastfeeding, you can start estrogen, either in the form of a birth control pill or as an estrogen patch in combination with a progestin-eluting IUD, depending on what you and your doctor decide is best for you. You can also make a plan for this transition while you are still pregnant or breastfeeding so the transition can be as smooth as possible.
The takeaway: Estrogen levels drop precipitously after pregnancy whether a woman is in perimenopause or not, and symptoms such as hot flushes and night sweats are common. Women who were perimenopausal prior to pregnancy can make a plan with their OB-GYN regarding when to start birth control pills or hormone therapy after delivery to proactively treat perimenopausal symptoms.
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