This study aims to determine when during gestation oxytocin receptor (OXTR) expression increases in the myometrium, which will contribute new insight to the management of obstetric hemorrhage and our understanding of normal and abnormal labor.

In this descriptive study, we will obtain myometrial tissue samples by core needle biopsy under ultrasound guidance in anesthetized women immediately following surgical abortion and from controls, all of whom are undergoing a separate planned obstetric/gynecologic surgery. Tissue studies will be performed on these biopsy samples to examine oxytocin receptor expression and function.

Inclusion Criteria:

• Women age 18-50
• Gestational age 14-26 weeks; or 6-13 weeks, 37-42 weeks, or non-pregnant (controls)
• Undergoing another planned surgical procedure with anesthesia (suction D&C, D&E, gravid hysterectomy, cesarean section, or laparoscopic tubal ligation)
• Able to give informed consent in English or Spanish

Exclusion Criteria:

To optimize biopsy safety, we will exclude patients with anticipated difficult cases, that have additional risks of hemorrhage, or those with features that limit ultrasound visualization.

Increased risk of hemorrhage:

• Anemia (Hgb < 9)
• Anticoagulation, bleeding disorder, or coagulopathy
• Multiple gestation
• Infection or sepsis

For ultrasound-guided procedures:

• Obese, BMI ≥ 40
• History of ≥2 cesarean sections
• Large fibroids or uterine anomalies obstructing view
• Other poor visualization
• Thin myometrium < 1cm

This is a study of reproductive age women over 18 years of age being performed at Oregon Health & Science University (OHSU) in Portland, OR. It will include subjects who present for pre-operative appointments in our outpatient Center for Women's Health Family Planning Clinic and OHSU Labor and Delivery.