The first stage of labor is complete following maximal cervical dilation and full effacement of the cervix.
The first stage of labor begins at the onset of labor and typically lasts 10-12 hours in a nulliparous patient and 6-8 hours in a multiparous patient. It is divided into latent and active phases, with the latent phase characterized by slow cervical dilation and slow cervical change. The latent phase ends when the cervix is dilated roughly 6 cm. The active phase follows the latent phase and is marked by more rapid cervical change and dilation. Maximal cervical dilation usually occurs around 10 cm.
Kripke writes that maternal positioning can alter the duration of the first stage of labor. Women in upright positions had a mean duration of labor one hour less than women in recumbent positions. Such women were also less likely to receive epidural analgesia.
Lauzon et al. review labour assessment programs which aim to delay admission of pregnant women who are not in the active stage of delivery. This delay of admission prevents women from undergoing unnecessary interventions. They found that in a study of 209 women, the women who were randomly assigned to the labour assessment unit spent less time in the labour ward, intrapartum oxytocics, and analgesics than compared to those admitted to the labour ward directly.
Illustration A shows the Friedman labor curve. Note that at the end of Stage I, the cervix is fully dilated and the fetus is close to delivery.
Answer 1: Delivery of the placenta marks the end of the third stage of labor.
Answer 3: Delivery of the infant marks the end of the second stage of labor.
Answer 4: A positive fern test confirms a rupture of membranes. Estrogens in amniotic fluid cause crystallization of the salts of amniotic fluid when it dries. These crystals resemble the shape of fern leaves under low microscopic power.
Answer 5: A positive fetal head station may indicate the progression of labor but does not define the beginning or end of any of the stages of labor.
Kripke C. Upright vs. recumbent maternal position during first stage of labor. Am Fam Physician. 2010 Feb 1;81(3):285
PMID:20112886 (Link to Abstract)
Lauzon L, Hodnett E. Labour assessment programs to delay admission to labour wards. Cochrane Database Syst Rev. 2001;(3):CD000936. Review.
PMID:11686969 (Link to Abstract)