Placenta praevia and low-lying placenta

If your 20-week scan report mentioned a low-lying placenta or placenta praevia, you’ve probably come home with more questions than answers. The short version is reassuring: a placenta that’s lying low at 20 weeks usually moves out of the way by itself, and even when it doesn’t, there’s a clear, well-worn plan for keeping you and your baby safe.

What it means. The placenta attaches wherever the embryo happened to implant, and sometimes that’s low in the uterus, near or over the cervix — the exit your baby needs at birth. If the placenta is close to the cervix it’s called low-lying; if it covers the opening, it’s placenta praevia.

Why it usually resolves. The placenta doesn’t actually crawl upwards — the lower part of your uterus stretches and grows through the second and third trimesters, which carries the placenta up and away from the cervix. This happens in the large majority of cases: around nine in ten placentas that are low at the mid-pregnancy scan are out of the way by the third trimester. That’s why the usual response to a low placenta at 20 weeks isn’t treatment — it’s simply a follow-up scan around 32 weeks to check where things have landed.

The symptom to know about: painless bleeding. Because the placenta sits over the part of the uterus that stretches most, praevia can cause episodes of bright red vaginal bleeding without pain, most often in the third trimester. Any bleeding in pregnancy deserves a same-day call to your midwife or maternity unit — and if bleeding is heavy, don’t wait or drive yourself: call 000. Many people with praevia never bleed at all, but knowing the plan in advance takes the panic out of it.

What your team may advise if the placenta stays low: avoiding penetrative sex and anything else your obstetrician specifically flags, keeping hospital within reasonable reach late in pregnancy, and sometimes a period of monitoring in hospital if there’s been bleeding. Recommendations genuinely vary case by case — with a praevia, “ask my team” beats any general rule, so don’t be shy about requesting specifics: what should I avoid, what should I watch for, when do I call?

What it means for the birth. This is the part that most changes plans, so it’s worth naming early: if the placenta is still covering or very close to the cervix near the end of pregnancy, a planned caesarean is the safe way for your baby to be born — labour and a vaginal birth would mean the placenta bleeding before the baby could get out. The timing is usually a few weeks before your due date, decided with your obstetrician. If a vaginal birth mattered a lot to you, it’s okay to grieve that plan a little; it’s also worth knowing that a planned caesarean for praevia is a calm, well-rehearsed procedure, and the parts of birth that matter most — meeting your baby, skin-to-skin, those first feeds — are all still yours.

A note on the emotional side: praevia has a way of putting a pregnancy “on watch”, and the wait between scans can feel long. Most of the time, the 32-week scan closes the story with one sentence — the placenta has moved, no restrictions. Until then, live normally within whatever limits your team has actually given you, rather than the stricter ones the internet will try to sell you.

If you’ve had any bleeding, new pain, or your baby’s movements have changed, contact your maternity unit straight away — and for heavy bleeding, call 000. For everything slower-burning, write your questions down and bring them to your next appointment; praevia is exactly the kind of diagnosis your team expects questions about.