Intrauterine (fetal) growth restriction: causes, monitoring and birth planning

Tommy’s explains that fetal growth restriction is a condition in which a baby has not grown as well as expected, sometimes called intrauterine growth restriction. NHS inform’s Ready Steady Baby describes it as babies being smaller and lighter than they should be for that stage of pregnancy.

The distinction from being small matters. Some babies are naturally small, some catch up and grow later in pregnancy, and most small babies are born healthy and grow into healthy children, according to NHS inform. Tommy’s says that most small babies do not have health problems; FGR is a narrower diagnosis that includes signs that the baby is not thriving or that the placenta is not working well.

Tommy’s lists the causes as the placenta not working as well as it should, problems with the baby, and infections such as CMV or toxoplasmosis, and adds that unfortunately it is not always known why FGR happens. NHS inform similarly lists the placenta not providing enough, a health condition in the baby, poor diet, smoking and pre-eclampsia.

Risk factors include a previous small baby or stillbirth, previous placental or blood pressure problems or pre-eclampsia, health conditions such as high blood pressure, kidney disease, diabetes, autoimmune disease, complicated heart disease or clotting problems, smoking or recreational drug use, high caffeine intake, being aged 40 or over and being underweight. Tommy’s notes that people of Pakistani, African or Black African Caribbean heritage may have a higher chance of a small, but not necessarily growth-restricted, baby, and that heavy vaginal bleeding in the second half of pregnancy can affect growth.

It stresses that FGR is unlikely to be due to anything you did before or during pregnancy. Steps that reduce the risk of pregnancy complications in general include stopping smoking, limiting caffeine to 200 mg a day, avoiding recreational drugs and alcohol, maintaining a healthy weight, taking folic acid and vitamin D, going to all antenatal appointments, and, if you are at risk of pre-eclampsia or placental problems, taking low-dose aspirin as advised from 12 to 36 weeks.

Tommy’s says the main sign is the baby not being the size expected for the stage of pregnancy. A midwife measures the bump from the top of the womb to the pubic bone, records it on a growth chart and advises an extra ultrasound if there is concern. An extra scan is a more accurate way of checking size and does not always mean something is wrong.

If concern continues, you will be offered closer monitoring. Tommy’s lists an umbilical artery Doppler scan to measure blood flow through the cord, more frequent growth scans, extra Doppler scans of blood flow in the baby’s brain and abdomen, a computerised cardiotocograph, and assessment of amniotic fluid. At each appointment blood pressure and urine protein are checked. You may be referred to a specialist if the baby is very small, small early in pregnancy or the Doppler scan is not normal.

Tommy’s says if your maternity team is concerned, you are likely to be advised to give birth before 38 weeks, and the best timing is discussed with you according to your circumstances. You may be able to have a vaginal birth with induction, or you may be advised to have a caesarean. You will be advised to give birth in a hospital with a specialist baby unit.

If the baby is likely to be born preterm you will be offered a course of corticosteroids to help the baby’s breathing, and if birth is before 34 weeks, magnesium sulphate, which helps reduce the risk of cerebral palsy. After the birth the baby is closely monitored.

Risks of FGR include a higher chance of stillbirth, being unwell at birth and needing neonatal care, according to Tommy’s and NHS inform, which is why it is important that it is spotted early.

Tommy’s says feeling your baby move is a sign they are well, there is no set number of normal movements, and from about 16 to 24 weeks you should feel more movement up until 32 weeks, after which movements should stay roughly the same until birth. Call your maternity unit and get checked straight away if your baby is moving less, movements feel weaker or movements have stopped.