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Oral contraceptive use among women aged 15 to 49: Results from the Canadian Health Measures Survey.

BACKGROUND
Oral contraceptives (OCs) have been available in Canada for over 50 years and are the most commonly used method of reversible contraception. OCs have evolved over time, with decreasing estrogen doses, new progestins, and different dosing regimens. Detailed data about OCs use among Canadian women are lacking.


DATA AND METHODS
Data from Statistics Canada's 2007/2009 and 2009/2011 Canadian Health Measures Survey (CHMS) were used to estimate OC use, by selected sociodemographic characteristics, cardiovascular risk factors, and estrogen dose and progestin type. Logistic regression was used to model relationships between OC use and sociodemographic factors.


RESULTS
An estimated 1.3 million (16%) women aged 15 to 49 reported taking OCs in the previous month. OC use decreased with age (30% among 15- to 19-year-olds; 3% among 40- to 49-year-olds). OC users were significantly more likely than non-users to be nulliparous, sexually active and Canadian-born. At ages 35 to 49, users were less likely than non-users to have one or more cardiovascular risk factors. Almost all (99%) OC users took combined formulations containing ethinyl estradiol (EE) and progestin. Two-thirds of OCs users took formulations containing 30 or more mcg of EE. Women aged 15 to 24 were more likely than those aged 35 to 49 to use lower-dose formulations (less than 30 mcg of EE).


INTERPRETATION
A substantial percentage of reproductive-aged Canadian women, particularly younger women, used OCs. OC use varied by sociodemographic and some cardiovascular risk factors. The majority took formulations containing 30 or more mcg of EE.