Influence of hypertension disorder complicating pregancy and its interaction with other factors on incidence of small for gestational age

Objective: To understand the influence of hypertension disorder complicating pregancy on the incidence of small for gestational age (SGA) and its interaction with other factors. Methods: A nested case-control study was conducted to analyze the influence of hypertension disorder complicating pregancy on the incidence of small for gestational age and evaluate the interaction between hypertension disorder complicating pregancy and other factors. Results: Data from 6 297 subjects were collected, including 836 (13.28%) pregnant women with hypertension disorder complicating pregancy, 789 (12.53%) infants who were small for gestational age. Compared with the pregnant women without hypertension disorder complicating pregancy, women with hypertension disorder complicating pregancy (aOR=2.185, 95% CI: 1.266-3.770), preeclampsia- eclampsia (aOR=5.322, 95% CI: 4.224-6.707) and with chronic hypertension complicated with superimposed preeclampsia (aOR=3.794, 95% CI: 2.190-6.573) had increased risk for the incidence of small for gestational age. The Interaction analysis showed that there was strong positive interactions between hypertension disorder complicating pregancy and premature birth on small for gestational age infants (RERI=5.260, AP=0.586, SI=2.941), (OR=2.331, 95%CI: 1.443-3.767). Addictive interaction was found between hypertension disorder complicating pregancy and placental abruption (RERI=5.631, AP= 0.522, SI=2.352), and between hypertension disorder complicating pregancy and female fetuses (RERI= 3.660, AP=0.374, SI=1.714), and between hypertension disorder complicating pregancy and oligohydramnios (RERI=10.619, AP=0.636, SI=3.093). However, no significant multiplication interaction was found. Conclusions: Hypertension disorder complicating pregancy is the risk factor of the incidence of small for gestational age. Hypertension disorder complicating pregancy also showed addictive interaction on the incidence of small for gestational age with female fetuses, placental abruption as well as oligohydramnios. There was addictive and multiplication interactions between hypertension disorder complicating pregancy and premature birth.