Correction to: Early pregnancy stage 1 hypertension and high mean arterial pressure increased risk of adverse pregnancy outcomes in Shanghai, China

We aimed to evaluate the influence of early pregnancy stage 1 hypertension and mean arterial pressure (MAP) on the risk of pregnancy complications, including gestational diabetes mellitus (GDM) and adverse pregnancy outcomes. Pregnant women without early pregnancy hypertension were consecutively recruited in 2010 in Shanghai, China. Total 6104 women with blood pressure (BP) <140/90 mmHg were categorized according to early pregnancy BP and MAP levels, respectively. Multivariate adjusted logistic regression and cox regression was used to test the potential associations. Finally 313 (5.1%) pregnant women identified as stage 1 hypertension. Compared with normotensive women, women with early pregnancy stage 1 hypertension increased the risk of gestational hypertension (GH) [Adjust odds ratio (AOR) 2.295, 95% confidence interval (CI) 1.578–3.338], GDM [AOR 1.185, 95% CI 1.010–1.391], preeclampsia [AOR 2.295 95% CI 1.578–3.338], preterm delivery [AOR 1.326, 95% CI 1.026–1.713]and infants with low-birth weight [AOR 1.487, 95% CI 1.082–2.045]; Compared women with MAP < 76 mmHg, the risk of GDM increased, with an adjust hazard ratio (AHR) of 1.387 (95%CI 1.048–1.835) for 76 ≤ MAP < 88 mmHg and an AHR of 1.451 (95%CI 1.053–1.998) for MAP ≥ 88 mmHg. Especially, high MAP levels (≥ 88 mmHg) are associated with GH [AOR 2.775, 95%CI 1.805–4.266], preeclampsia [AOR 3.936, 95%CI 2.358–6.570] and preterm delivery [AOR 1.412, 95%CI 1.035–1.926]. In summary early pregnancy stage 1 hypertension is associated with adverse pregnancy outcomes. Relative higher BP levels in early pregnancy, especially elevated MAP levels should be aware by clinicians to decrease the risk of pregnancy complications.