Early versus late onset of hypertensive disorders in twins—The placental perspective

OBJECTIVES: Early and late hypertensive disorders in pregnancy (HDP) are different entities in singleton gestations, with earlier onset associated with higher rates of placental maternal vascular malperfusion lesions (MVMs). It is still not known if this distinction apply for twin gestations as well. METHODS: Retrospective study of women with DCDA twin gestations and HDP (2001–2015), with a placental pathology evaluation. Placental lesions were classified according to the Amsterdam criteria. Pregnancies with early onset HDP (≤34 weeks) were compared with pregnancies with late onset HDP (>34 weeks). RESULTS: Out of 1655 twin deliveries, 161 (9.7%) were complicated by HDP: 77 (47.8%) had preeclampsia, and 84 (52.2%) had gestational hypertension. Forty patients (24.8%) had early onset HDP. Early HDP was associated with a higher rate of 1 MVMs (p=0.01), ≥2 MVMs (p=0.009) and with a lower rate of chronic villitis (p=0.02). In multivariable analysis, using late HDP as reference, early HDP was associated with a higher prevalence of ≥1 MVMs (aOR 1.9, 95% CI 1.1–3.5, p=0.03) and ≥2 MVMs (aOR 2.6, 95% CI 1.05–6.3, p=0.04). Early HDP was also less associated with chronic villitis (aOR 0.2, 95% CI 0.05–0.9), as chronic villitis is usually associated with a more advanced gestational age. CONCLUSIONS: While the mechanism underlying HDP in singleton and twins’ gestations may be different, similar to singleton pregnancies, early onset (≤34 weeks gestation) of HDP in twins’ gestation is associated with a higher prevalence of MVM's, suggesting of reduced placental perfusion in early onset HDP in twins.