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Table 1 Basic characteristics of the participants according to the presence or absence of placenta accreta spectrum

From: Risk factors for placenta accreta spectrum: findings from the Japan environment and Children’s study

VariablePAS (+)
N = 202
PAS (−)
N = 90,352
P value
Maternal age, mean years (SD)32.4 (5.3)31.2 (5.0)< 0.001a
Maternal age category, % (n)
 ≤ 19 years1.0 (2)0.8 (743)0.001b
 20–24 years6.4 (13)9.1 (8192)
 25–29 years21.8 (44)27.7 (25011)
 30–34 years32.2 (65)35.4 (32025)
 35–39 years29.7 (60)22.4 (20274)
 ≥ 40 years8.9 (18)4.5 (4107)
Primiparous, % (n)37.6 (76)40.6 (36643)0.397b
ART pregnancy, % (n)19.3 (39)2.9 (2619)< 0.001b
Maternal smoking status, % (n)
 Never smoker81.7 (165)82.2 (74294)0.029b
 Quit smoking during early pregnancy9.9 (20)13.0 (11742)
 Smoking during pregnancy8.4 (17)4.8 (4316)
Number of IAs, % (n)
 081.2 (164)84.2 (76073)0.468b
 113.4 (27)11.6 (10506)
 ≥ 25.4 (11)4.2 (3773)
BMI, kg/m2, % (n)
 < 18.516.2 (32)16.2 (14471)0.925b
 18.5–24.972.2 (143)73.1 (65362)
 ≥ 2511.6 (23)10.8 (9618)
Endometriosis, % (n)5.9 (12)3.7 (3301)0.084b
Uterine myoma, % (n)8.9 (18)6.1 (5475)0.090b
Adenomyosis, % (n)1.0 (2)0.3 (295)0.099c
Uterine anomaly, % (n)1.5 (3)0.3 (256)0.021c
Gestational age, mean weeks (SD)38.7 (2.1)38.7 (2.1)0.964a
Placenta previa, % (n)8.9 (18)0.6 (513)< 0.001b
Cesarean section, % (n)16.8 (34)19.3 (17301)0.378b
Maternal blood transfusion, % (n)19.3 (39)0.4 (416)< 0.001b
  1. PAS Placenta accreta spectrum, SD Standard deviation, ART Assisted reproductive technology, IA Induced abortion, BMI Body mass index
  2. a P value from t-test
  3. b P value from chi-square test
  4. c P value from Fisher exact test
  5. P < 0.05 is statistically significant