IVF, gestational diabetes and preeclampsia
It does appear that those who become pregnant through IVF have an increased the chance of contracting gestational diabetes4. This does not appear to be related to the age of the pregnant woman or person. It also appears that IVF may increase the number of pregnant women and people who have preeclampsia in pregnancy, from around 1/100 to 6/1005. It might be that one or more of these conditions mean that an early birth is recommended, but this should only happen if it appears that the pregnancy ending earlier is less risky than it continuing.
Sometimes, doctors may advise induction simply because there is an increased chance of these conditions, whether or not the woman or person actually has them! Of course, personalised care – and logic – means that this should not happen! Only if the woman or person has one of these conditions and only if the severity of the condition means that, on balance, the risk to continuing the pregnancy is higher than the risk of induction would there be any reason to consider it. Even then, the decision is the pregnant woman or person’s, and theirs alone.
Small for gestational dates, fetal growth restriction and IVF
You may hear that babies who are conceived through IVF are more likely to be born with a low birth weight. There are three main reasons for this:
- Babies born following IVF are more likely to be born prematurely (either after spontaneous labour or early induction just because they’re IVF babies!)
- They are more likely to be pregnancies of twins or more compared to unassisted conception, and twins or multiples are often smaller than singletons
- A very small number of babies conceived by IVF may be more likely to be growth restricted in utero compared to babies conceived without assistance
It’s important to separate out a baby who is born with a low birth weight for the first two reasons listed above from babies who have actual growth restriction. It’s already very difficult to work out which babies are struggling with their growth, rather than just being babies who are small but healthy. Babies who are estimated to be below the 10th percentile for their gestational date may be considered to be growth restricted, even though most of these will be healthy. This equates to around 3-7% of all babies being classed as growth restricted in unassisted pregnancies, even though almost all will be fine6. IVF appears to increase the number of babies who are estimated to be below the 10th percentile by around 1 to 3 more babies per 100 pregnancies7.
Although most babies who are estimated to be under the 10th percentile will be perfectly healthy, a few will be genuinely affected by a problem such as reduced blood flow from the placenta. It is estimated that, of the babies who are estimated to be below the 10th percentile, 0.97%, or just under 1 in 100 of these babies, are at risk of stillbirth8.
The question we then need to know is whether induction at term would reduce the numbers of these babies who died before birth, and so far that doesn’t seem to be the case. One randomised control trial9 comparing induction at term with expectant management for women whose babies were considered to be small for gestational dates showed no decrease in the numbers of stillbirths, although this may have been because there weren’t enough people involved in the trial to show a difference. The UK’s Saving Babies’ Lives care bundle included an element where additional monitoring of small babies was a key factor, including recommendations for early birth if considered necessary. The bundle itself is thought to have reduced the stillbirth rate by a fifth – from 10 in 1000 to 8 in 100010. However, it significantly increased the interventions at term including induction and caesarean, with all the harm that they can cause, including to subsequent pregnancies where the risk of stillbirth and ectopic pregnancy increases by a small amount after a previous caesarean11. Furthermore, the Saving Babies’ Lives bundle had many separate elements including a focus on supporting women and people to stop smoking in pregnancy, and raised awareness of their baby’s movements, and we don’t know whether it was these elements, or the early births, which caused this reduction in stillbirths.