Effects of continuous versus cyclical oral contraception: a randomized controlled trial.
BACKGROUND
Continuous oral contraception may better suppress the ovary and endometrium, lending itself to the treatment of other medical conditions.


OBJECTIVE
Our objective was to determine the effects of continuous vs. cyclical oral contraception.


METHODS
This was a randomized double-blind trial.


METHODS
This trial was performed at an academic medical center in Pennsylvania.


METHODS
A total of 62 healthy women with regular menses were included in the study.


METHODS
Cyclical oral contraception (21-d active/7-d placebo given for six consecutive 28-d cycles) vs. continuous (168-d active pill) therapy using a monophasic pill (20 microg ethinyl estradiol and 1 mg norethindrone acetate) was examined.


METHODS
The primary outcome was vaginal bleeding, and secondary outcomes included hormonal, pelvic ultrasound, quality of life, and safety measures.


RESULTS
There was no statistically significant difference in the number of total bleeding days between groups, but moderate/heavy bleeding was significantly greater with the cyclical regimen [mean 11.0 d (sd 8.5) vs. continuous 5.2 d (sd 6.8); P = 0.005], with both groups decreasing over time. Endogenous serum and urinary estrogens measured over six cycles were significantly lower (P = 0.02 and 0.04, respectively) in the continuous group than the cyclical group. Women in the continuous group also had a smaller ovarian volume and lead follicle size over the course of the trial by serial ultrasound examinations. The Moos Menstrual Distress Questionnaire showed that women on continuous therapy had less associated menstrual pain (P = 0.01) and favorable improvements in behavior (P = 0.04) during the premenstrual period.


CONCLUSIONS
Continuous oral contraception does not result in a reduction of bleeding days over a 168-d period of observation but provides greater suppression of the ovary and endometrium. These effects are associated with improved patient symptomatology.
Department of Obstetrics and Gynecology, Pennsylvania State University College of Medicine, M.S. Hershey Medical Center, 500 University Drive, H103, Hershey, Pennsylvania 17033, USA. RSL1@PSU.EDU.
Richard S
RS
Legro
Jaimey G
JG
Pauli
Allen R
AR
Kunselman
Juliana W
JW
Meadows
James S
JS
Kesner
Richard J
RJ
Zaino
Laurence M
LM
Demers
Carol L
CL
Gnatuk
William C
WC
Dodson
D000328:Adult; D003278:Contraceptives, Oral, Hormonal / Q000008:administration & dosage*; D004311:Double-Blind Method; D004958:Estradiol / Q000097:blood; D004970:Estrone / Q000031:analogs & derivatives / Q000652:urine; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008597:Menstrual Cycle / Q000187:drug effects*; D010053:Ovary / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology; D011276:Pregnanediol / Q000031:analogs & derivatives / Q000652:urine; D011374:Progesterone / Q000097:blood; D011788:Quality of Life; D012044:Regression Analysis; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013739:Testosterone / Q000097:blood; D014463:Ultrasonography
D003278:Contraceptives, Oral, Hormonal; D012738:Sex Hormone-Binding Globulin; C022270:pregnanediol-3 alpha-glucuronide; C015856:estrone-3-glucuronide; D004970:Estrone; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D011276:Pregnanediol