Randomization
preterm labor
PRETERM BIRTH, IRREGULAR UTERINE CONTRACTIONS, SEVERE PREECLAMPSIA, PRETERM LABOR
Participants were divided into three groups (1:1:1) by a block-of-three randomization using sealed envelopes, performed by the research team. Envelopes were opened by the delivery nursing team, when mothers commenced preterm labor and had at least four regular uterine contractions in 20 min with cervix dilatation > 4 cm or when mothers had preterm birth scheduled due to severe preeclampsia.