Although much investigation has been done on the use of ferning in the second and third trimesters, particularly with the development of rapid protein clinical assays, there appears to be lower ferning rates in clinical practice with traditional techniques compared to previous published research on the subject. Much of the older study designs are lacking in detail and lack a large enough sample sizes at each gestational age to appropriately interpret the significance of ferning results by gestational age. Additionally, a large premise for the current tests used to diagnose rupture of membranes is based on these older studies. Given this, we propose collecting amniotic fluid vaginally to evaluate for the presence of ferning in the second trimester to determine if there is a difference in ferning based on gestational age as well as the time interval after rupture of membranes in which ferning can observed on microscope examination.

Inclusion Criteria:

• 18 years or older
• English speaking
• singleton or multi fetal gestation
• between 15 and 24 weeks gestation
• undergoing elective pregnancy termination

Exclusion Criteria:

• known rupture of membranes or anhydramnios

Prospective observational study including pregnant women 18 years or older who present for pregnancy termination, between 15 and 24 weeks gestation. Women with a singleton or multi-fetal gestation, who have previously established dating based on a first trimester ultrasound or ultrasound prior to 22 weeks gestation, will be included. Exclusion criterion are women who are less than 18 years of age, non-English speaking, and rupture of membranes or anhydramnios (no measurable amniotic fluid on ultrasound) at the time of data collection in the operating room.