Results
In total, 104,102 records were identified during the study period. Of
those, 1,994 records from women with multiple gestation pregnancies and
7,698 records of women with missing data were excluded from the analysis
(Figure 1). After applying our exclusion criteria, the data of 94,410
maternal participants were included in the analysis. Among 94,410
participants, 416 women had placental abruption and 93,994 women were
without placental abruption. The prevalence rate of placental abruption
was 0.4% (416/94410). Almost half (44.1%) of the placental abruption
cases occurred prematurely before the gestational age of 37 weeks
(Figure 2A).
Table 1 summarizes the maternal characteristics and obstetric outcomes
of the participants stratified by the presence and absence of placental
abruption.
The rate of CS in women with placental abruption was 62.2%, which was
significantly higher than that in women without placental abruption
(18.6%, P <0.001). Among women with placental
abruption, the rate of CS dropped rapidly after 37 weeks of pregnancy
(Figure 2B).
Table 2 shows the results of the logistic regression analyses. After
adjusting for potential confounding factors, history of placental
abruption (aOR: 3.5, 95% CI: 1.3–9.6, P =0.013), ART
(aOR: 1.7, 95% CI: 1.1–2.7,P =0.021), maternal age <20 years (aOR: 2.8, 95% CI:
1.2–6.5, P =0.016), maternal age ≥35 years (aOR: 1.7, 95% CI:
1.1–2.5, P =0.024), smoking during pregnancy (aOR: 1.7, 95% CI:
1.2–2.5, P =0.003), and chronic hypertension before pregnancy
(aOR: 4.0, 95% CI: 2.5–6.2, P <0.001) were associated
with placental abruption. When no parity was set as a reference, no
association was observed between the number of parities and risk of
placental abruption.