Poster session II Diabetes, labor, medical-surgical-disease, obstetric quality & safety, prematurity, ultrasound-imaging: Abstracts 237 – 386| Volume 206, ISSUE 1, SUPPLEMENT , S150, January 01, 2012

316: Estimating the impact of pelvic immaturity & young maternal age on fetal malposition


      Fetal malposition, specifically occiput posterior and transverse (OP/OT), is associated with higher intra-partum morbidity. We tested the hypothesis that young maternal age & pelvic immaturity are risk factors for fetal malposition.

      Study Design

      In a cohort study of all nulliparous teen (≤18 years old) deliveries over a 4-year period at one institution, fetal head position at time of delivery was collected and correlated with maternal characteristics and outcome data. Using Risser staging observations, pelvic maturity age was set at 16 and accordingly the women were divided into two groups (younger vs. older teens). Group comparisons and analysis was performed using Fishers exact, Student's t-test, and logistic regression modeling.


      Older teen mothers (16-18 years old, n=609) had higher rates of malposition (22% vs. 12%, p=0.02) when compared with younger teens (≤15 years old, n=98). Among all women with a malpositioned fetus, older teens had a higher body mass index (BMI: 32.6 vs. 28.5, p=0.04) and subsequent need for Cesarean delivery (69% vs. 33%, p=0.02) when compared with their younger counterparts (Figure 1). Although younger teens were more successful in having a vaginal delivery (67%) with an OP/OT position, it was at the expense of a 25% rate of severe perineal laceration (3rd/4th degree).


      Obesity, and not young maternal age or pelvic immaturity appears to be associated with fetal malposition. The direct association with increasing pre-pregnancy BMI and the long-term impacts of the high rates of Cesarean delivery in this young population underscores the need for more public health attention.