Table 1.

Main data at baseline in all cases, cases who delivered a singleton, all controls, and controls who delivered a singletona

All Cases (n = 120)Cases Who Delivered a Singleton (n = 91)All Controls (n = 297)Controls Who Delivered a Singleton (n = 267)Patients versus Controls (all cases referred)Patients versus Controls (only singleton delivery)
Maternal age, years, mean ± SDb31.26 ± 5.3631.16 ± 5.3329.44 ± 5.3129.41 ± 5.31P = 0.00160.043
Nulliparous, %c6061.5360.3061.4NSNS
Week of referral, median (range)d12 (4 to 38)13 (4 to 38)12 (4 to 32)12 (4 to 32)NSNS
Caucasian race, %c89.168977.477.2P = 0.005P = 0.022
Educational level > 8th grade, %ce61.3465.945.446P = 0.0053P = 0.001
BMI, mean ± SDbf23.34 ± 4.6423.44 ± 4.7822.54 ± 3.6122.51 ± 3.63NSNS
  • a No statistical difference between patients who delivered and all referred cases or between all controls and controls who delivered for all parameters.

  • b t test.

  • c χ2 test.

  • d Mann–Whitney test.

  • e Educational level available data: 119 of 120 in cases and 295 of 297 in controls.

  • f BMI, body mass index available data: 119 in cases and 296 in controls.