When a miscarriage happens, most women are told it was chromosomal and there was nothing to be done. That answer is sometimes correct. But it is far from complete, and the number most women are given is often more alarming than the data actually supports.
The Most Common Causes
Chromosomal abnormalities in the embryo are a leading cause of early loss, and the rate does rise with age, but not nearly as steeply as most women are told. In women under 35, about 20 percent of eggs are chromosomally abnormal, meaning 80 percent are normal. In women 36 to 39, that rises to 30 to 40 percent abnormal. In women 40 to 44, it is 40 to 55 percent abnormal. Even in your 40s, more than half of your eggs can still be chromosomally normal. And it is worth asking why the rate of abnormal eggs may be elevated in the first place, because that rate is influenced by egg quality, which is modifiable.
Luteal phase insufficiency is an underrecognized cause. Progesterone should rise above 5 ng/mL within 48 to 72 hours after ovulation, then climb above 10 ng/mL, ideally 15 to 20, for most of the luteal phase. When it drops too early or never rises adequately, the uterine lining cannot support implantation through the critical window. This is frequently missed because progesterone is often tested only once, if at all. Causes of a luteal phase defect include hypothyroidism, PCOS, endometriosis, over-exercise, insulin resistance, and eating disorders.
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Immune and Uterine Factors
An overactive immune system can cause the body to treat a developing embryo as a foreign invader. Elevated natural killer cell activity, antiphospholipid syndrome, and HLA compatibility issues between partners are all immune-related causes that are rarely included in a standard miscarriage workup. Antiphospholipid syndrome alone is present in 5 to 10 percent of recurrent loss cases.
Uterine structural issues, including polyps, fibroids inside the cavity, or a uterine septum, can prevent proper implantation. Chronic endometritis, a subclinical infection of the uterine lining, is present in up to 66 percent of women with recurrent pregnancy loss and is often missed without a hysteroscopy and biopsy.
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What to Do After a Miscarriage
Request testing for the factors above if you have had two or more losses, which is now the clinical threshold for a full evaluation, not three. Ask about reproductive immunology if you have lost chromosomally normal embryos. Commit to the egg quality protocol: CoQ10, omega-3s, vitamin D, methylfolate, anti-inflammatory nutrition. Support progesterone naturally through sleep, stress reduction, and targeted nutrients. And give yourself time to grieve. The body and the heart both need it.
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This post is for educational purposes only and is not a substitute for personalized medical advice. Please consult your own doctor before making changes to your care.