Placental insufficiency: when the placenta is not working well in pregnancy

The placenta is the organ that develops in pregnancy to connect you with your baby. “Placental insufficiency” is a descriptive term for a placenta that is not working as well as it should. UK charity Tommy’s uses almost this wording when it lists the causes of fetal growth restriction (FGR): the placenta not working as well as it should, problems with the baby such as a genetic or developmental condition, and infection such as CMV or toxoplasmosis. It also says we do not always know why FGR happens.

Tommy’s defines fetal growth restriction as a condition where a baby has not grown as well as expected. If a baby’s estimated size is in the smallest 3 in 100, or in the smallest 10 in 100 with signs that the placenta is not working well, they are said to have fetal growth restriction. A baby in the smallest 10% on size alone is considered small (small for gestational age), which is not the same thing.

Tommy’s describes the way concerns are followed up: growth measurements and ultrasound scans, with extra scans of blood flow, the baby’s heart tracing and the amniotic fluid if growth is a worry.

Tommy’s says several things can increase the risk of fetal growth restriction. Many cannot be changed, and Tommy’s notes that it is unlikely to be to do with anything you did before or during pregnancy.

• A previous small baby or previous stillbirth.

• Problems with the placenta, blood pressure or pre-eclampsia in a previous pregnancy.

• Health conditions such as high blood pressure, kidney disease, diabetes, autoimmune disease, complicated heart disease or blood clotting problems.

• Smoking tobacco or using illegal or recreational drugs, and having more than the recommended amount of caffeine.

• Being aged 40 or over, or being underweight (BMI under 18.5).

• Heavy vaginal bleeding, especially in the second half of pregnancy.

Tommy’s says the main sign of fetal growth restriction is the baby not being the size they should be for the stage of pregnancy, which is why growth is measured at antenatal appointments. A midwife uses a tape measure from the top of the womb to the pubic bone, and if there are concerns advises an extra ultrasound scan, which Tommy’s says can be worrying but does not always mean something is wrong.

Your baby’s movements are the part you can check yourself. The NHS says you should start to feel your baby move between 16 and 24 weeks, that there is no set number of movements each day and no need to count kicks, and that the important thing is to get to know your baby’s usual pattern. It says to call your midwife or maternity unit immediately if your baby is moving less than usual, you cannot feel your baby moving, or there is a change in the usual pattern, not to wait until the next day, and not to use a home doppler to check the heartbeat.

Tommy’s gives the same message: from 16 to 24 weeks you should feel movements increasing until about 32 weeks, after which they should stay roughly the same, and you should call your maternity unit and be checked straight away if your baby is moving less, movements feel weaker or movements have stopped.

If your maternity team is concerned about how your baby is growing, Tommy’s says you will be offered closer monitoring with extra ultrasound scans. Options it lists include an umbilical artery Doppler scan measuring blood flow through the umbilical cord, more frequent growth scans, extra Doppler scans of blood flow in the baby’s brain and abdomen, a computerised cardiotocograph tracing of the baby’s heart, and assessment of the amniotic fluid.

At every appointment your blood pressure is checked and your urine tested for protein. You may be referred to a specialist doctor if your baby is very small, was found to be small early in pregnancy or the umbilical artery Doppler is not normal. Tommy’s notes that if you are at risk of pre-eclampsia or of problems with the placenta, you should be advised to take low-dose aspirin (150 mg each evening) from 12 to 36 weeks.

Tommy’s says babies with FGR may be at greater risk of being stillborn, of being unwell when born or of dying soon after birth, and may need to be born prematurely or cared for in a neonatal unit, because the things that can cause FGR, such as the placenta not working well, increase the risk of other complications. Going to all your antenatal appointments means any complications can be found and monitored or treated quickly.

There is no treatment that repairs the placenta. Care is about monitoring and choosing the best time for birth. Tommy’s says it is very likely that you will have your baby before 38 weeks, that you may be able to have a vaginal birth with labour induced or may be advised to have a caesarean section, and that you will be advised to give birth in a hospital with a specialist baby unit in case your baby needs extra care.

Tommy’s lists changes that reduce the risk of pregnancy complications in general: stopping smoking, limiting caffeine to 200 mg a day, not using illegal or recreational drugs, avoiding alcohol, maintaining a healthy weight, taking vitamin D and folic acid, eating a healthy balanced diet, going to all antenatal appointments and taking any medicines prescribed by your doctor.

It also advises contacting your GP, midwife or maternity unit if you have bleeding, and calling your midwife at any time if you are concerned about the size of your bump.

In the UK, routine antenatal care and extra monitoring for growth concerns are provided by NHS midwives, obstetric teams and maternity units. Private antenatal scans are available, but because a private scan sits outside the NHS monitoring pathway, results that suggest a problem should be shared promptly with your NHS midwife or maternity unit.

Whichever route you use, a change in your baby’s movements is a reason to contact your NHS maternity unit immediately.