In 3-4% of pregnancies, fetus may have early-onset growth restriction that can lead to premature birth, serious complications or even death before, during or after delivery. A new calculator, developed from a study by the Placental Insufficiency Unit of the Obstetrics Service at Vall d’Hebron University Hospital and the research group in Maternal and Fetal Medicine at Vall d’Hebron Research Institute (VHIR) will allow to know, from the moment of diagnosis, the risk of complications that a fetus with early growth restriction will have during pregnancy or at the time of birth. This way, individualized counseling will be possible and it will allow parents to understand the diagnosis and the evolution of the pregnancy, thus reducing the uncertainty and anxiety that results.
The study, which has been published in Acta Obstetricia et Gynecologica Scandinavica, consisted of the follow-up of 173 pregnant women with fetuses that had early-onset growth restriction, that is, diagnosed before the 32nd week of gestation. On average, the women were in the 23rd week of gestation and the fetal weight was below the 10th centile, that is, much lower than the average for age.
In order to design the calculator, researchers took into account the mother’s characteristics, the existence of abnormalities in the ultrasound, the week of gestation when the diagnosis of growth restriction was made, as well as the levels of some factors related with the malfunction of the placenta. These factors, known as sFlt1/PlGF, increase when the placenta does not receive enough oxygen and therefore indicate and increased risk of complications in the mother and fetus. In the study, preterm birth and perinatal complications were registered, which appeared in 81 cases, mainly related to respiratory problems of the fetuses. With all this information, an algorithm or calculator was developed to predict the risk of these complications in a personalized way.
“This calculator allows us to give an individualized risk to patients who have a fetus with growth restriction, and we can do it from the moment of diagnosis”, explains Dr. Manel Mendoza, specialist physician of the Obstetrics Service, head of the Placental Insufficiency Unit of the Vall d’Hebron University Hospital and researcher of the Maternal and Fetal Medicine research group at VHIR. “Until now, giving this information to patients was very difficult because it was the physician himself who, based on his or her experience, gave an approximate date of birth or the consequences that the fetuses could have”, he adds. The only way to follow up, therefore, was to perform frequent and repeated ultrasounds to assess the progression of the fetuses.
With this new methodology, specialists are able to give a risk of preterm birth for each case and can explain to the family what complications are expected and with what probability. “Pregnant women can benefit from personalized advice. The fact that there is not so much uncertainty about the diagnosis means that parents can understand much better the situation and the complications that the low weight of the fetus can lead to”, says Dr. Mendoza, who states that “this way, parents feel less anxiety and are much more involved in the recommendations and follow-up that are offered to them”.
Two ways of calculating risk that can be adapted to all centers
The researchers of the study analyzed the relationship between clinical data and risk of complication for a specific person. Thus, it was seen that the best way to know this risk was analyzing the sFlt-1/PlGF factors, which increase when the placenta does not work properly and have a great capacity to predict complications in fetuses with early growth restriction. However, these markers are not yet available in all centers as their importance for assessing fetal development is a fairly recent discovery.
In order for all centers to have a way to calculate and predict risk, regardless of their technical capabilities, the researchers considered it essential to develop a second option without the need to know the levels of placental factors sFlt-1/PlGF. This alternative takes into account only the ultrasound data and the mother’s characteristics and allows a similar calculation of the risk. “Although the best option is to use placental factors, this second variant will allow all centers to provide information on possible complications, since it is based on data that are routinely collected”, concludes Dr. Mendoza.
The calculator validated in this study is already being used in the Fetal Medicine Unit of the Obstetrics Service at Vall d’Hebron University Hospital when there is a diagnosis of early-onset growth restriction. To ensure that it can be applied to all centers in the future, it is also accessible online for everyone.