Learning Objective #1: Describe the ethnically determined anthropometric variation of the human head and pelvis

Learning Objective #2: Discuss the impact of same and different ethnicities of biological parents in contributing to the diagnosis of "failure to progress" and, ultimately, delivery by c-section

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Background: Cesarean delivery is the most frequently performed major surgery in the United States. However, cesarean delivery rates vary widely across populations. The literature indicates genetic and ethnic influences play an important role in birth outcomes such as fetal weight, duration of pregnancy, and mode of delivery. These differences persist after adjustment for socio-economic and geographic variables. Anthropometric variation amongst different ethnic groups suggests that it may be the shape and configuration of the fetal head and maternal pelvis, not size alone, that contributes to the common diagnosis of "failure to progress" in the US. Because there are many different racial and ethnic combinations of biologic parents in the US, it is conceivable that the c-section rate may be higher than in countries where there is less ethnic variation of partners.

Purpose: This study explores the impact of same and different ethnicities of biological parents in contributing to the c-section rate in the US.

Sample: The study sample was derived from all births occurring in Texas (n=1,091,237) as recorded by the Texas Department of Health during the three-year period from 1999 through 2001. Cases used in the data analysis were those in which race/ethnicity was documented on the birth certificate for both the mother and the father. Singleton deliveries achieved by primiparous vaginal birth and primary c-section were then examined.

Preliminary Data Analysis: Births in which the mother's race or ethnicity differed from the father's race or ethnicity were achieved more frequently by c-section delivery than were births to parents of the same racial or ethnic background. Chi square analysis indicates that there is a statistically significant difference in these groups.

Implications: Identification of additional factors in diagnosing fetal head/maternal pelvis incongruency enables the health care provider to anticipate at-risk patients prior to the onset of labor.