Low PAPP-A in Pregnancy: What Does It Mean for My Baby?

Low PAPP-A in pregnancy means the level of a placenta hormone, measured in the first-trimester combined screening blood test, was lower than expected. NHS hospital leaflets say most pregnancies with a low level progress as normal, with babies born at term and at the expected weight. In a small number, it may suggest the placenta is not working as well as it could, so extra monitoring is often offered.

A low PAPP-A result is a screening signal read by your care team, not a diagnosis. It cannot tell anyone how an individual pregnancy will turn out. This guide explains what the result is, what extra care may look like and what to ask.

Whatever your PAPP-A result, some symptoms in pregnancy need help straight away. Do not wait for a planned scan or appointment. Contact your maternity unit or local emergency services if any of the following happen.

• Heavy vaginal bleeding, severe tummy pain, shoulder pain, or feeling faint or dizzy. The NHS advises calling emergency services for bleeding with these signs.
• Your baby moving less than usual, a change in their usual pattern of movements, or no movements felt. The NHS says to call your midwife or maternity unit immediately, even at night, rather than waiting until the next day.
• A severe headache that does not ease with simple painkillers, blurred vision or flashing lights, pain below the ribs, or sudden swelling of the face, hands or feet. These can be signs of pre-eclampsia and need to be checked straight away.
• Your waters breaking, signs of labour or any bleeding before the date you were advised to have your baby.

PAPP-A stands for pregnancy-associated plasma protein-A. It is a hormone made by the placenta, the organ that passes oxygen and nutrients to the baby through the umbilical cord. It plays a part in the healthy growth of both the placenta and the baby.

In the UK, PAPP-A is measured as part of the combined test, offered in early pregnancy alongside a measurement of fluid at the back of the baby's neck (nuchal translucency) and a second hormone, hCG. The main purpose of the combined test is to estimate the chance of Down's, Edwards' and Patau's syndromes. A low PAPP-A level is sometimes reported separately because of its link with placenta function.

Not on its own. PAPP-A is one of several pieces of information combined into the overall screening chance. If your combined screening result was reported as lower chance, one NHS leaflet states that a low PAPP-A level does not mean the baby has a higher chance of Down's, Edwards' or Patau's syndrome.

If your combined result was higher chance, that is a separate result with separate options. Our guide to NT scan results explains how that chance is reported and what tests may be offered next.

Studies have linked low PAPP-A with a higher chance of some placenta-related problems. NHS leaflets list a baby being smaller than expected, pre-eclampsia (high blood pressure with protein in the urine) and, less often, pregnancy loss later in pregnancy. If growth slows or pre-eclampsia develops, the chance of an earlier birth also rises.

These are increased chances across groups of pregnancies, not predictions for one person. Many people with low PAPP-A have no complications at all. The point of extra monitoring is to notice any change early, so your team can plan care if it is needed.

Care differs between hospitals and countries, and some services review their pathways as evidence changes. Common elements described in NHS leaflets include:

• Extra growth scans: regular ultrasound scans to measure the baby's growth and wellbeing. One NHS trust starts these monthly from around 28 weeks; the number offered usually depends on how the baby is growing.
• Blood flow and fluid checks: some scans also measure blood flow through the placenta or umbilical cord (Doppler) and the amount of fluid around the baby.
• Blood pressure and urine checks at antenatal appointments, to look for early signs of pre-eclampsia.
• A change of care plan: some services move care from midwife-led to consultant-led, and review the timing and place of birth with you as the pregnancy goes on.
• Support to stop smoking, if relevant, because smoking reduces oxygen reaching the baby through the placenta.

Some maternity services discuss low-dose aspirin after a low PAPP-A result. NHS leaflets say there is evidence it may help blood flow through the placenta and may reduce the chance of pre-eclampsia. Practice varies, including when it starts and stops.

Do not start aspirin on your own. Ask your midwife or obstetrician whether it is recommended for you, how to take it and when to stop. Aspirin can interact with other medicines, including over-the-counter and herbal products, so tell the team everything you take.

A result like this can be worrying. Writing down questions before the appointment can help you leave with a clear plan.

• What was my overall combined screening result, and is the low PAPP-A reported separately?
• Does this result change my care plan, and who is now responsible for it?
• How many growth scans will I have, from when, and what will each one check?
• Is aspirin recommended for me? If so, how and until when should I take it?
• Which symptoms should I report, and which number do I call day or night?
• If the growth scans are normal, does my care return to the usual pathway?
• Could this affect the timing or place of birth?

On SameCase, patients and verified doctors share de-identified cases. Reading how others with a low PAPP-A result described their scan schedules and conversations can help you spot questions you had not thought to ask, such as how often scans were arranged or what was checked. Other people's pregnancies cannot predict yours, and nothing there replaces the advice of your own maternity team.