Use of LMWH, divided by presumed high dose and presumed prophylactic dose in third trimester compared to no treatment, and labor dystocia. Women with treatment in first and/or second trimester are excluded.

***** The presumed high dose group is based on underlying diagnoses with indications for treatment dose and high dose prophylaxis: thrombosis during present pregnancy, previous and present thrombosis, antiphospholipidantibody syndrome with previous or present thrombosis, mechanical heart valve, and continuous warfarin or LMWH treatment before the pregnancy (30 days). Previous several thrombosis and antithrombin deficiency were not included. The presumed prophylactic group includes the residual women with LMWH treatment in third trimester.

* Model 1: Adjustments for maternal characteristics: treatment with LMWH, age, height, BMI, smoking during pregnancy, diabetes, hypertensive disease, assisted reproduction, education, year of birth and onset of labor.

** Model 2: Adjustment for characteristics in model, and gestational length at birth.

*** Model 3: Adjustment for characteristics in model 1, gestational length at birth and epidural analgesia.

**** Model 4: Adjustment for characteristics in model 1, gestational length at birth, epidural analgesia and birth weight.

Use of LMWH, divided by presumed high dose and presumed prophylactic dose in third trimester compared to no treatment, and labor dystocia. Women with treatment in first and/or second trimester are excluded.