DALLAS – Two molecular biomarkers in amniotic fluid seem to predict preterm premature rupture of membranes (pPROM) and subsequent premature delivery in women whose fetuses undergo surgical repair of spinal cord defects.
Matrix metalloproteinase–8 (MMP-8) and lactic acid levels were significantly higher in these women than in a comparator group of women who did not deliver a premature infant after the repair, Aikaterini Athanasiou, MD, said at the meeting sponsored by the Society for Maternal Fetal Medicine.
“Based on this pilot study, it appears that elevated amniotic levels of lactic acid and MMP-8 at time of surgery might identify a subset of women with increased susceptibility for pPROM and shorter time to delivery,” said Dr. Athanasiou, a fellow in obstetrics and gynecology at Cornell University, New York. She presented the work on behalf of primary author Antonio Moron, MD, PhD, of the Federal University of São Paulo.
Dr. Athanasiou was part of the Cornell team that conducted molecular assays on amniotic fluid samples drawn from 26 women carrying fetuses about to have corrective surgery for spinal defects in the fetuses. The women were all patients at the Federal Hospital of São Paulo. Samples were drawn immediately before surgery commenced, frozen, and shipped to Cornell for assay.
After surgical repair, 7 of the women (27%) later experienced pPROM and 19 did not.
At baseline, there were no significant differences between the groups. Women were a mean age of 32 years, with a mean of two prior pregnancies. There were no differences in prior cesarean and vaginal births, smoking status, and fetal gender. The defect was most commonly a myelomeningocele (about 70% of each group). Rachischisis was next most common, occurring in 27% of the pPROM group and 21% of the non-pPROM group. There were two cases of encephalocele, both in the non-pPROM group.
The length of surgery was not significantly different between those who experienced pPROM and those who did not (121 vs. 130 minutes). Wound healing time was 7 days for each group, as was the mean length of hospital stay.
Both groups went a mean of 57 days from surgery to delivery, although the fetal gestational age was almost a week younger in the pPROM group (33.7 vs. 34.4 weeks). These infants were also smaller at birth (2,247 g vs. 2,410 g).
The Cornell team examined five potential biomarkers in each amniotic fluid sample: MMP-8, MMP-9, MMP-2, lactic acid, and interleukin-6 (IL-6). The levels of IL-6, MMP-2, and MMP-9 were similar between groups.
However, lactic acid was significantly higher in the pPROM group (7.1 vs. 5.9 mU/mL). MMP-8 was also significantly elevated in the pPROM group (1.7 vs. 0.6 mcg/mL).
Dr. Athanasiou and her colleagues also observed an inverse relationship between MMP-8 levels and gestational age at delivery, which was statistically significant. There was also an inverse relationship between lactic acid levels and gestational age, but this did not reach statistical significance.
“While further investigations are needed to verify our findings, our data suggest that these differences are present before fetal surgery and that an increase in intra-amniotic anaerobic glycolysis as evidenced by elevated lactic acid may enhance MMP-8 production, which will weaken the maternal-fetal membranes,” Dr. Athanasiou said. “The mechanism may not be related to inflammation, as evidenced by the lack of association between pPROM and IL-6.”
She had no financial disclosures.
SOURCE: Moron A et al. Am J Obstet Gynecol. 2018 Jan:218(1);S64.