49.此時胎兒監測器（fetal monitor）呈現子宮收縮情況，下列何者為最常見？
(A)子宮持續收縮（tetanus contraction）
(B)子宮規則收縮
(C)子宮無收縮
(D)子宮偶發性收縮

沒有找到文獻支持這樣的說法，甚至有文獻認為收縮和出血無關...

Twenty-two women > 24 weeks' gestation with a central placenta praevia were monitored to determine if an increase in uterine activity precedes bleeding in patients with central praevias. Monitoring of all subjects began at 26.3 +/- 4.4 weeks and continued until 37 weeks (or delivery if preterm). All subjects had at least one haemorrhage, 7 women had 2, and 4 subjects had 3 episodes of bleeding. Only 3 patients delivered at term while the remainder (86%) delivered preterm. The gestational age at first episode of bleeding was 29.1 +/- 3.6 weeks and at delivery was 34.3 +/- 3.3 weeks. Nine women (41%) had an increase in uterine activity above baseline the day or the day preceding the first haemorrhage. The increase in uterine activity was not statistically significant when compared to the 6 days prior to bleeding when all 22 patients were considered.

Magann EF, Johnson CA, Gookin KS, Roberts WE, Martin RW, Morrison JC. Placenta praevia: does uterine activity cause bleeding? Aust N Z J Obstet Gynaecol. 1993 Feb;33(1):22-4. doi: 10.1111/j.1479-828x.1993.tb02045.x. PMID: 8498933.