Fear of weight gain is the most common reason given by young women for not using or for discontinuing oral contraception. Health professionals are frequently concerned about the long-term effects on cardiovascular risk factors and changes in plasma lipid levels associated with the use of oral contraceptives. Most available data on these concerns are based on women older than 20 years, and little is known about the effects of oral contraceptives on adolescent metabolic and physiologic systems. Lloyd and colleagues used data accumulated over nine years to investigate patterns of weight change and cardiovascular risk factors in young women using oral contraceptives.

They studied a cohort of white girls who averaged 12 years of age in 1990 and were attending public school in central Pennsylvania. As part of a study of calcium and bone metabolism, the girls were assessed every six months for four years, then every year, for a total of nine years of follow-up. At age 21, 39 participants had been using oral contraceptives for at least six consecutive months, with a mean duration of 28 months. These young women were compared with 27 members of the cohort who had never used oral contraceptives by age 21.

All participants had uneventful reproductive maturation, with a mean age of 13.4 years at menarche. Both groups reported an average of 10 menstrual periods per year. Twenty-three percent of the oral-contraceptive users reported smoking compared with 7 percent of the nonusers.

Oral-contraceptive users had a significantly lower body mass index (BMI) compared with nonusers, but the groups did not differ in other measures of body composition or exercise scores. Exercise scores and longitudinal analyses that adjusted for BMI at entry to the study showed no significant differences between oral-contraceptive users and non-users in measures of body weight and composition. For cardiovascular risk factors, oral-contraceptive users had significantly greater increases in total cholesterol levels, low-density lipoprotein levels, and serum triglyceride levels than nonusers. Oral-contraceptive users had nonsignificantly greater increases in high-density lipoprotein levels.

The authors conclude that oral-contraceptive usage is not associated with excess gain in weight, BMI, or body-fat percentage in teenaged girls but is associated with a change in blood-lipid patterns. The clinical significance of the changes in lipid profiles is unknown.