Could a mid-pregnancy blood test help plan for early preterm births?

Findings from a new study show that low circulating blood levels of placental growth factor (PLGF) during mid-pregnancy is associated with a risk for early preterm birth, defined as a birth before 34 weeks gestation.The test could help patients and physicians monitor and plan for an early preterm birth to ensure better outcomes for the birthing parent and infant. Placental growth factor (PLGF) rises throughout gestation as a healthy placenta develops. It reaches a peak at 28 weeks. Previous research suggests low levels of PlGF contribute to preeclampsia.The prospective, observational study involved 9,037 pregnant participants who planned to delivery their baby at Mount Sinai Hospital in Toronto between 2000 and 2023. Their healthcare provider tested PLGF levels at 24 to 28 weeks, the same time as the routine screening for gestational diabetes. A total of 107 participants had a PLGF level lower than 100 picograms per millilitre (pg/mL), with more than half of these patients giving birth within 50 days of the blood test (i.e., at 31 to 35 weeks gestation). A PLGF level less than 100 pg/mL was associated with a 48 times higher risk of preterm birth than having a PLGF higher than 100 pg/mL. Low PLGF was also associated with a risk of iatrogenic births, which make up most early preterm births.Read: New guidance on caring for newborns at risk of withdrawal due to parental substance useThe test appears to stand alone. Weight, race and previous pregnancy outcomes did not affect the association between low PLGF and preterm births.“This means it’s a very simple test to interpret,” said Dr. John Kingdom, senior author of the study, an obstetrician and clinician-scientist at Sinai Health and professor at University of Toronto’s Temerty Faculty of Medicine. “It doesn’t matter how tall you are, whether you’re Black or white, or if you’ve had a baby before, the test interpretation remains valid regardless of those inputs.”With a blood test alerting physicians and patients to the risk of an early preterm birth, they could more readily take necessary precautions. “It starts with self-monitoring for elevated blood pressure and perhaps taking anti-hypertensive medications to keep it under control,” explained Dr. Rachel Gladstone, lead author of the study and a fourth-year obstetrics and gynecology resident at the University of Toronto. “And if you originally had plans to deliver at a community hospital or remote location, you could decide to receive care at a tertiary centre, which may be safer for both mother and baby than emergency transport to such centres for unanticipated complications.”Most centres in Canada have the capability and expertise to include PLGF in mid-pregnancy blood tests. It is already included in an early risk assessment for Down’s Syndrome (trisomy 21). In the U.K., PLGF is measured in the first trimester to screen for risk of preeclampsia.Read: Dramatic differences: Why do Black women face a higher maternal morbidity rate than their white counterparts?Incorporating it into routine screening in mid-pregnancy would ultimately be a funding decision, Dr. Kingdom said in a press release from the university.“It is very obvious based on the data that large-scale screening would deliver health systems cost savings. I’m optimistic we’ll see this happen within three to five years.”The next step is to run a randomized clinical trial to further decide if testing PLGF level at mid-pregnancy is an effective tool for predicting early preterm birth and producing better health outcomes. A cost-effectiveness study is also needed, the authors note.The research is published in JAMA Network Open.

Could a mid-pregnancy blood test help plan for early preterm births?

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