Direct injection of corticosteroids into the fetus compared with injection into the mother for improving fetal outcomes when the mother is at risk of preterm birth
What is the issue?
Babies born preterm (before 37 weeks of pregnancy) are at risk of dying, having bleeding into their brain and problems with their breathing because their lungs are not fully developed. Corticosteroid treatment given to the mother before early birth has been shown to be effective in preventing these problems and has become standard care in many countries. The common method of giving corticosteroid is by injecting into the mother's muscles. The corticosteroid treatment then transfers across the placenta (known as transplacental transfer) to the fetus. This treatment has its own risks, such as reducing fetal growth and brain development as well as increasing the baby's risks of diseases such as diabetes and high blood pressure. Injecting corticosteroid directly into the fetus is feasible with ultrasound guidance.
Why is this important?
Injecting corticosteroid directly into the fetus, instead of injecting into the mother's muscles, may prevent the risk of increased blood pressure, increased blood glucose levels, and susceptibility to sepsis in the mother. It may also reduce the amount of corticosteroid needed. However, it carries a risk of infection of the uterus and fetal injury, and may cause preterm labour and birth. We found that there have been no studies assessing the benefits and harms of direct injection into the fetus compared with injection into the mother.
What evidence did we find?
We searched for evidence on 25 October 2017 and we did not find any completed randomised controlled trials that assess the benefits and harms of direct injection of corticosteroid into the fetus compared with injection into the mother, for women who are at risk of preterm birth. We found two studies, but one was not a randomised controlled trial, and in the other study the methods were unclear, so we have contacted the study authors for further information.
What does this mean?
We need further studies to assess the effects of injecting corticosteroid directly to the fetus compared with injecting into the mother's muscles. The babies in these trials need to be followed up over a long period so that we can monitor the effects of corticosteroids on childhood development, including impairments or disabilities such as cerebral palsy. We need good-quality randomised trials, to establish if one method is better than the other.