RESUMO
<p><b>INTRODUCTION</b>Low levels of pregnancy-associated plasma protein-A (PAPP-A) might be associated with abnormal placentation, leading to the development of preeclampsia during late gestation. We aimed to determine the association between low serum PAPP-A levels and rates of preeclampsia in Thai women with otherwise low-risk pregnancies.</p><p><b>METHODS</b>A cohort study was conducted on consecutive singleton pregnancies undergoing first trimester screening for fetal Down syndrome at a tertiary centre hospital. A prospective database was assessed for patient records, including PAPP-A levels, pregnancy outcomes and obstetrics complications. Pregnancies with potential causes of preeclampsia were excluded. Enrolled women were categorised into two groups: women with normal PAPP-A levels (≥ 10th percentile; control group); and those with low PAPP-A levels (< 10th percentile; study group). The main outcome measure was rate of preeclampsia.</p><p><b>RESULTS</b>Of 6,887 women screened, 3,830 were available for analysis and 167 were excluded due to potential confounders. Of the remaining 3,663 women enrolled, 357 women were categorised as having low PAPP-A levels and 3,306 had normal PAPP-A levels. The prevalence of preeclampsia (8.4% vs. 2.6%) and early-onset preeclampsia (i.e. before 34 weeks of gestation) (1.1% vs. 0.1%) was significantly higher (relative risk 3.27 and 9.26, respectively) in women from the study group than in the control group.</p><p><b>CONCLUSION</b>Pregnancy with PAPP-A levels < 10th percentile was significantly associated with an increased risk of preeclampsia that tended toward early development. Therefore, pregnant women with low PAPP-A levels in the first trimester should be considered to be at increased risk of preeclampsia.</p>