New Research on Alpha-Fetoprotein has Important Clinical Implications
Important Question
Researchers recently used BORN data to conduct a large retrospective cohort study to answer an important question. Are high levels of alpha-fetoprotein (AFP) in a pregnant person’s blood - drawn as part of enhanced first trimester screening (eFTS) - linked to placental problems such as severe preeclampsia, fetal growth restriction and stillbirth? If yes, clinicians need to monitor these patients more closely. If not, extra surveillance is not required.
Previous studies exploring this question have been smaller, have not included comparison positive-control groups, and have yielded conflicting results. One of the strengths of this population-based study was the large sample size (important when predicting uncommon outcomes such as preterm birth due to placental complications). It also directly compared the association of first-trimester AFP with placenta-mediated complications to that of the traditional serum markers.
What’s at Stake?
In second trimester screening, high levels of AFP are associated with the placental complications described above, and clinicians need to monitor the pregnant person and baby more closely in such cases.
In practical terms this means clinicians may need to order extra ultrasounds, monitor their patient’s blood pressure more closely, and recommend induction before 40 weeks. Extra monitoring can have logistical, financial, and emotional consequences for the pregnant person (e.g. scheduling extra appointments, taking time off work, worrying about the wellbeing of the baby). Increased surveillance and interventions such as labor induction, also impose additional costs on the healthcare system and potential risks for the pregnant individual.
Care providers have been uncertain, however, whether the association between elevated AFP and placental complications can be extrapolated to the first trimester. Given the uncertainty, many care providers are using the same approach described above (i.e. increased antenatal surveillance).
A Good-News Answer
The researchers found that elevated first-trimester AFP was not an independent risk factor for placenta-mediated complications.
The results are relevant to obstetricians, midwives, general practitioners, and maternal fetal medicine specialists as they have implications for clinical practice. The data indicates the following:
- Healthy pregnant people with elevated first-trimester AFP should not be considered at increased risk of placental complications (as long as other eFTS serum markers are within the normal range)
- Elevated first-trimester AFP levels alone should not trigger extra antenatal surveillance.
With regard to limitations, this study did not have information on other risk factors and biomarkers for preeclampsia and did not have information on Aspirin prophylaxis (designed to prevent preeclampsia). The authors note, however, that the rates of Aspirin use in Ontario are currently very low, even when indicated.
Pregnancy is a vulnerable time, often accompanied by many concerns. The study recommendations are important as they may prevent unnecessary anxiety about placental complications and fetal wellbeing. The recommendations could also help reduce unnecessary maternal-fetal monitoring, resulting in cost savings for Ontario's healthcare system.
For more details, see the article: Maternal First-Trimester Alpha-Fetoprotein and Placenta-Mediated Pregnancy Complications.
Spreading the Word
In addition to publishing their results, the researchers are sharing this information on the Prenatal Screening Ontario website. Dr. Nir Melamed - study lead - says they are also in the process of writing an SOGC technical update/guideline on this topic and hope to present it at future SOGC conferences.