How do I protect the placenta next time?

Much of what goes wrong later in pregnancy — preeclampsia, a baby who stops growing well, some stillbirths — traces back to how the placenta implants in the first trimester. Some specialists focus heavily on the placenta from the earliest weeks. Here's which parts of that approach have evidence, and what you can ask for.

Low-dose aspirin, if you qualify

Strong evidence 81 mg a day, starting after 12 weeks — ACOG says ideally before 16 — and continuing until delivery. In women at higher risk it means about 15% less preeclampsia, 20% fewer preterm births and 21% fewer baby deaths around the time of birth, according to the US Preventive Services Task Force. In the ASPRE trial, women screened as high-risk who took 150 mg nightly had 62% less preterm preeclampsia — the kind that leads to delivery before 37 weeks.

If you have antiphospholipid syndrome, this is different. Aspirin for APS is usually started before conception or at the positive test, alongside heparin, as part of a treatment plan — not at 12 weeks. Follow your specialist's timing.

You qualify with one of: a previous pregnancy with preeclampsia, twins or more, chronic high blood pressure, diabetes before pregnancy, kidney disease, lupus, or antiphospholipid syndrome.

Or with two of: a first pregnancy, age 35 or over, BMI over 30, IVF, a family history of preeclampsia, being Black, lower income, more than ten years since your last birth, or a previous adverse outcome such as stillbirth or a baby born small.

It's often not offered unless you ask. One honest limit: aspirin protects against placental complications later in pregnancy. It has not been shown to prevent early miscarriage itself.

First-trimester placental screening

Moderate evidence At 11 to 14 weeks, blood flow in the uterine arteries (a Doppler ultrasound), your blood pressure and a placental protein called PlGF together pick out higher-risk pregnancies far better than a checklist of risk factors — it's how the ASPRE trial chose who got aspirin. It's routine in the UK and much of Europe and patchy in the US, so it's worth asking whether it's available to you.

This screening grew out of research in the 1980s and 1990s on blood flow to the placenta, including work by maternal-fetal medicine specialist Alexander Kofinas showing that high resistance in the uterine arteries predicted preeclampsia and growth restriction.

If you have antiphospholipid antibodies

Moderate evidence Aspirin plus heparin is the treatment with real evidence behind it for antibody-related loss. What to know if your antibodies don't fit the formal criteria.

If you bleed early and have miscarried before

Moderate evidence Progesterone. In a trial of 4,153 women with bleeding in early pregnancy, those who had had three or more miscarriages had 72% live births on progesterone versus 57% on placebo. The UK's NICE now recommends it for women with bleeding and a previous miscarriage. Without bleeding, it hasn't been shown to help.

Earlier, closer scans

Emerging evidence Some specialists scan the placenta and the baby's growth more often from early pregnancy after a placental complication, and some studies link placental changes seen on second-trimester ultrasound to poorer outcomes. It's reasonable to ask for, but it isn't yet standard guidance.

What hasn't held up

Insufficient evidence Heparin for inherited clotting variants, and steroids, IVIG or intralipids for unexplained loss. The largest heparin trial found 72% versus 71% live births. European guidelines advise against routine use of the others. If one is offered, it's fair to ask what evidence supports it for your situation.