Effect of oral contraceptives and intrauterine devices on midcycle myometrial contractions.
OBJECTIVE
To determine the effects of oral contraceptives and intrauterine devices (IUDs) on midcycle myometrial contractions.


METHODS
Prospective cohort study.


METHODS
Academic tertiary care center.


METHODS
Thirty four patients who received oral contraceptives, 20 patients with an IUD, 28 controls, and 6 patients who were evaluated before and after oral contraceptive use.


METHODS
All groups underwent endovaginal ultrasonography to visualize myometrial contractions at midcycle.


METHODS
Contractions were analyzed for direction, frequency, amplitude, and distance traveled.


RESULTS
Fifty percent of women taking oral contraceptives had no contractions, whereas all controls had contractions. Women taking oral contraceptives also had decreased frequency, amplitude, and distance traveled of contractions compared with controls. Women evaluated before and after taking oral contraceptives had decreased frequency, amplitude, and distance traveled of contractions. Women with an IUD had significantly more asymmetrical uncoordinated contractions, with decreased frequency and distance traveled, compared with controls.


CONCLUSIONS
Oral contraceptives dramatically suppressed midcycle contractility. Since the normal midcycle peak of estrogen is suppressed by oral contraceptives, these contractions may be regulated by cyclic estrogen and progesterone. Uncoordinated contractions in IUD bearing women indicate that the foreign body reaction of the IUD affects the normal physiology of these contractions.
Maslow
Kenny D
KD
Department of Obstetrics, Gynecology, and Reproductive Sciences, Women's Hospital, Health Sciences Center, University of Manitoba, Winnipeg, Manitoba, Canada. kennymaslow@hotmail.com
Lyons
Edward A
EA
D000328:Adult; D015331:Cohort Studies; D003276:Contraceptives, Oral / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007434:Intrauterine Devices; D008597:Menstrual Cycle / Q000502:physiology*; D011446:Prospective Studies; D014463:Ultrasonography; D014590:Uterine Contraction / Q000187:drug effects* / Q000502:physiology*; D014599:Uterus / Q000000981:diagnostic imaging
D003276:Contraceptives, Oral