Risk factors for severe maternal morbidity in patients with hypertensive disorder of pregnancy: A retrospective study

Abstract

Objective: To identify significant risk factors associated with severe maternal morbidity(SMM) in patients with hypertensive disorder of pregnancy (HDP).

Methods: This retrospective study analyzed clinical data from patients with HDP who delivered at Fujian Maternity and Children Health Hospital between January 2013 and March 2022. Univariate logistic regression analysis was performed to identify risk factors for developing SMM. Significant risk factors (P < 0.05) were considered for inclusion in multivariate logistic regression using stepwise regression with forward and backward selection.

Results: Of 3133 HDP patients included in the study, 365 met the diagnostic criteria of SMM and were included in the SMM group, while 2768 patients comprised the control group. The SMM group had a significantly higher incidence of gestational hypertension diagnosed at ≤ 34 weeks of gestation compared to the control group (30.14% vs. 12.64%, p<0.0001). Patients in the SMM group had a higher incidence of previous history of preeclampsia compared to the control group (1.64% vs. 0.25%, p=0.0001). Logistic regression analysis identified parity (OR, 1.37; CI, 1.05-1.78; p=0.0205), gestational age of diagnosis (OR, 2.22; CI, 1.68-2.92; p<0.0001), iron supplementation (OR, 2.31; CI, 1.83-2.93; p<0.0001), and preeclampsia (OR, 3.10; CI, 2.42-3.98; p<0.0001) as significant risk factors for SMM. Stepwise regression analysis confirmed that parity (OR, 1.43; CI, 1.17-1.73; p=0.0004), gestational age of diagnosis (OR, 2.32; CI, 1.77-3.05; p<0.0001), iron supplementation (OR, 2.30; CI, 1.82-2.90; p<0.0001), and preeclampsia (OR, 3.34; CI, 2.63-4.24; p<0.0001) remained significantly associated with SMM.

Conclusion: Gestational age of diagnosis, iron supplementation, and history of preeclampsia were identified as risk factors of SMM in patients with HDP. Our results can help identify high-risk patients for early recognition and management of SMM.

Keywords: Hypertensive disorder of pregnancy; Iron supplementation; Preeclampsia; Risk factors; Severe maternal morbidity.

Fig.1

Case-screening flowchart.

Supplementary Fig.1

Urine routine tests of pregnant women in the SMM and non-SMM groups at 24 weeks of gestation and one week before or after diagnosis (delivery). Urinary tests are shown on the left, while specific gravity is depicted on the right.

Supplementary Fig.2

Blood routine tests at 24 weeks of gestation & one week before or after the diagnosis (delivery).

Supplementary Fig.3

Lipid profiles including total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides at 24 weeks of gestation and one week before or after the diagnosis (delivery).

Supplementary Fig.4

Liver function tests including ALT, GGT, conjugated bilirubin, and unconjugated bilirubin at 24 weeks of gestation and one week before or after the diagnosis (delivery).

Supplementary Fig.5

Renal function tests including blood urea nitrogen, creatinine, uric acid, carbon dioxide binding capacity, and serum cystatin C at 24 weeks of gestation and one week before or after the diagnosis (delivery).

Supplementary Fig.6

Coagulation function tests including fibrinogen and fibrinogen degradation products at 24 weeks of gestation and one week before or after the diagnosis (delivery).

Supplementary Fig.7

Electrolytes and blood glucose levels at 24 weeks of gestation and one week before or after the diagnosis (delivery). These include serum calcium, serum magnesium, lactate dehydrogenase, and fasting blood glucose.