The analysis of placental biomarkers in blood allows for improved monitoring and care of pregnancies with low birth weight fetuses. This is the conclusion of a multicenter study led by Dr. Manel Mendoza from the Maternal and Fetal Medicine group of the Vall d’Hebron Research Institute (VHIR) and the Obstetrics and Gynecology Service of the Vall d’Hebron University Hospital. Recently published in the journal Nature Medicine, the work highlights that this method allows for distinguishing pregnancies at higher risk and, consequently, for more personalized monitoring to reduce perinatal, neonatal and maternal complications.

One of the main challenges in obstetrics is the care of pregnancies with low birth weight fetuses (below the 10th percentile of weight). This group includes fetuses that are small for their gestational age and fetuses with growth retardation. The latter are especially relevant, since, in addition to low birth weight, they tend to present more serious complications, both during pregnancy and during labor and after birth.

To differentiate between small for gestational age fetuses and those with growth retardation, the weight of the fetus is currently taken into account and studies are carried out with Doppler ultrasound. However, there are centers that do not have qualified personnel or this technology and, in addition, there are no standardized protocols. “Differentiating between these two conditions, which have such different risks of complications, is very important for making decisions. For example, clinical guidelines recommend advancing delivery to week 37 in fetuses with growth retardation, while in small fetuses we can wait until week 40”, explains Dr. Manel Mendoza, head of the Placental Insufficiency Unit at the Vall d’Hebron University Hospial and researcher in the Maternal and Fetal Medicine group at the VHIR.

In order to find new tools to better classify pregnancies, the researchers in this work have studied the blood levels of two placental biomarkers (sFlt-1/PlGF ratio), which had previously shown the ability to predict other pregnancy complications. Values ​​above 38 indicate a high risk of complications (growth retardation), while values ​​below 38 are typical of small fetuses with less risk.

The study was carried out with 1088 pregnant women with fetuses weighing below the 10th percentile from more than 20 hospitals throughout the State. In half, monitoring was carried out from the 36th week of gestation following the standard protocol (Doppler ultrasounds), and, in the other half, placental biomarkers in blood were analyzed. On the one hand, the appearance of two common complications in cases with growth retardation was studied, such as neonatal acidosis (lack of oxygen at birth) and the need for a cesarean section due to the presence of alterations in the fetal heart rhythm.

The results showed that in the cases in which biomarker analysis had been performed, there was the same incidence of these complications, approximately 10% in each group. In other words, the use of biomarkers is as effective as Doppler ultrasounds in preventing these complications. “We demonstrate that it is a simple alternative technique useful in centers where Doppler technology is not available, and it improves access to quality care”, says Dr. Mendoza.

Reduction de complications and an attention more personalized

The study also highlights a decrease in other complications of pregnancy, childbirth and the newborn, such as postpartum hemorrhage, and respiratory complications in newborns, in the group in which the analysis of placental biomarkers was performed, compared to the standard method.

In addition, it was observed that this new method reduces the number of premature labor inductions, since it better identifies fetuses where the risk is lower. In this way, it allows labor to be safely delayed, until weeks 39 or 40 in most cases, unlike the standard protocol, with which labor often has to be induced at weeks 37 or 38. “These results show that, with biomarkers, we can better classify pregnancies according to the real risk of complications. If classified correctly, some of the inductions of labor before 39 weeks can be avoided, which carry a greater risk of cardiovascular, neurological, metabolic or respiratory effects in the newborn”, assures Dr. Mendoza.

Additionally, a reduction in complications in pregnant women, such as preeclampsia, was confirmed, as previous studies have shown that biomarker analysis can also help identify the high risk of this disorder.

“This new approach represents another step towards more personalized medicine and more physiological and less invasive pregnancy monitoring. It reduces discomfort and anxiety associated with unnecessary medical interventions and, at the same time, improves the outcomes of the pregnant woman and the baby”, concludes Dr. Mendoza.

These biomarkers are already available in most public and private centers, and it is expected that they will soon be incorporated into the portfolio of services of the Catalan health system for the monitoring of low-birth-weight fetuses.