Mid pregnancy PlGF Screening: A Promising Tool for Identifying Risk of Early Preterm Birth, Study Reveals

The placental growth factor is a protein involved in blood vessel development within the placenta. PlGF levels in pregnant individuals can indicate how well the placenta is functioning, and lower levels have been linked to complications like preeclampsia and intrauterine growth restriction. Early preterm birth, defined as birth before 32 weeks of gestation, poses significant risks for both the mother and the newborn. Premature infants often face complications such as respiratory distress syndrome, neurological issues, and long-term developmental challenges. However, a universal screening strategy has not yet been established, hindering the ability to deliver targeted and effective interventions.

Against the above background, Rachel A. Gladstone, Department of Obstetrics & Gynecology, University of Toronto, Toronto, Ontario, Canada, and colleagues aimed to assess the effectiveness of mid-pregnancy PlGF screening in identifying pregnancies with the highest risk of early preterm birth.

For this purpose, the researchers conducted a prospective cohort study at an urban, tertiary care center between 2020 and 2023, involving pregnant individuals with singleton pregnancies who received routine prenatal care. Participants underwent a PlGF test during gestational diabetes screening at 24-28 weeks. The study analyzed data from January to May 2024.

The primary outcome was early preterm birth (before 34 weeks), with secondary outcomes including iatrogenic and spontaneous preterm birth, preeclampsia, stillbirth, and small-for-gestational-age birth weight.

The investigation revealed the following findings:

• Among 9,037 pregnant individuals, 156 (1.7%) experienced early preterm birth (52 spontaneous, 104 iatrogenic).
• The area under the curve (AUC) for PlGF and early preterm birth was 0.80.
• Low PlGF level was associated with early preterm birth, showing:
  • Positive likelihood ratio (LR): 79.4
  • Negative LR: 0.606
  • Specificity: 99.5%
  • Negative predictive value: 98.9%
• Time to birth was significantly reduced for those with PlGF levels below 100 pg/mL, with more than 50% delivering within 50 days.
• Individuals with low PlGF levels accounted for over 30% of subsequent stillbirths (adjusted relative risk [aRR], 36.78).
• More than 50% of patients requiring iatrogenic early preterm birth had low PlGF levels (aRR, 92.11).
• The AUC for iatrogenic early preterm birth was 0.90.

The findings indicate that mid-pregnancy PlGF testing could be a potential screening tool for identifying individuals at high risk for early preterm birth.

"Further randomized trials are necessary to assess the impact of widespread implementation of PlGF screening," the researchers concluded.

Reference:

Gladstone RA, Ahmed S, Huszti E, et al. Midpregnancy Placental Growth Factor Screening and Early Preterm Birth. JAMA Netw Open. 2024;7(11):e2444454. doi:10.1001/jamanetworkopen.2024.44454