This study compared the performance of a monthly injectable contraceptive (containing norethisterone enanthate and estradiol valerate) to a combined oral contraceptive (containing levonorgestrel and ethinyl estradiol) in adolescents. Over 12 months, 124 adolescents used the injectable and 127 used the oral contraceptive. Adolescents using the injectable were found to have higher psychosocial risk factors. While discontinuation rates were similar between the groups after 12 months, the injectable was associated with increased reports of menstrual irregularities and symptoms like dysmenorrhea and breast tenderness. Only one pregnancy occurred, in the oral contraceptive group. The study concluded the monthly injectable is a suitable

1. J Pediatr Adolesc Gynecol (2009) 22:25e31
Original Studies
Comparative Performance of a Combined Injectable
Contraceptive (50 mg Norethisterone Enanthate Plus 5mg
Estradiol Valerate) and a Combined Oral Contraceptive
(0.15 mg Levonorgestrel plus 0.03 mg Ethinyl Estradiol)
in Adolescents
´
Ramiro C. Molina, MD, MPH, Jorge Z. Sandoval, MD, Adela V. Montero, MD, Pamela G. Oyarzun,
´ ´
MD, Temıstocles G. Molina, BS, and Electra A. Gonzalez, SW, MSc
Center for Adolescent Reproductive Medicine, Faculty of Medicine, University of Chile, Santiago, Chile
Abstract. Study Objective: To compare in a regular non- Keywords. Injectable monthly contraceptive—
clinical trial experience the efficacy, acceptability, and con- Contraception in high risk adolescents
tinuation rates of an injectable contraceptive containing 50
mg norethisterone enanthate plus 5mg estradiol valerate
(IC) and an oral contraceptive containing 0.15 mg levonor-
gestrel plus 0.03 mg ethinyl estradiol (OC), among adoles-
cent users. Introduction
Design: A total of 251 adolescents ages 14e19 were fol-
lowed during 12 months. The IC group (124 subjects) was Prevention of the first pregnancy in adolescents is
studied for 1044 cycles and the OC group (127 subjects) a challenge for health care professionals. Lack of sex-
was studied for 1368 cycles. The users were not assigned ual education, poor reproductive health care, limited
in a random selection. Information was collected from clin- access to contraception at this age, and the heteroge-
ical records. Groups were compared using Pearson chi- neous cultural patterns of earlier fertility are the main
square, odds ratio (95% confidence interval), t-test, and
barriers.1 Another difficulty is inadequate access to
proportion difference test.
Results: The IC group had significant differences in acceptable contraceptive methods for this age group.
baseline social risk, confidence, psychiatric problems, con- Hormonal oral contraceptives and condoms are the
sumption of alcohol, and number of sexual partners. At 12 most widely known methods among teenagers in
months, the IC group showed significant decrease in weight Chile. However, they are not well informed about
and increase in hypermenorrhea. In the OC group, dysmen- injectables.2
orrhea decreased, and hypomenorrhea and regular cycles Clinical experience with adolescents shows that or-
were significantly more frequent. One pregnancy occurred al contraceptives containing low doses of estrogens
in the OC group (Pearl Index: 0.88). Final continuation (35 mg or less) do not have adverse effects on health,
rates at 12 months were 41.9% and 37.8% for IC and are highly effective with proper use, and induce excel-
OC, respectively. lent cycle control. There are some problems, however,
Conclusions: The monthly injectable is a recommended
with oral contraceptive (OC) use: the chance of miss-
contraceptive option for adolescents, especially for those
facing psychosocial risk factors. ing a pill, non-compliance, and the difficulty in con-
cealing the use of this method. Follow-up in our
Center showed 60 % discontinuation rates during
the first year among adolescents using the pill to pre-
vent the first pregnancy.2
Other factors that put adolescents at risk are: early
This study has been funded by the Faculty of Medicine, University of
Chile, Santiago, Chile.
sexual initiation associated with mental health prob-
Address correspondence to: Ramiro Molina Cartes, MD, Casilla lems, poor communication with their families, pro-
Postal: 70.011-7 Independencia. Santiago, Chile.; E-mail: miscuity, and consumption of tobacco, alcohol, and/
rmolina@med.uchile.cl or drugs.3
Ó 2009 North American Society for Pediatric and Adolescent Gynecology 1083-3188/09/$34.00
Published by Elsevier Inc. doi:10.1016/j.jpag.2008.07.010

2. 26 Molina et al: Comparison of Injectable and Oral Contraceptives
For some adolescent populations, the ideal contra- respectively, had discontinuation. These subjects were
ceptive method would be a reversible one, for which not included in the final analysis.
continuation does not depend on the user. Intra- Since most consulting adolescents at the Center
uterine devices (IUD) fulfill these requirements. In choose OC, in order to have similar size of compari-
Chile, however, physicians are reluctant to use IUDs son groups, within a week of the IC user’s first visit,
in young nulligravid women and some adolescents we selected a matching OC user for each IC user,
are reluctant to undergo IUD insertion.2 Implants whose age was within a year of the IC user’s age.
could be another contraceptive choice for this group. Participants did not show differences regarding
Their use, however, may not be easy to conceal and age, activity, referral source to the Center, schooling
the cost is higher. A third possible method would be and school grades. Routing interviews at the Center
the injectable containing depomedroxyprogesterone revealed that only 17% of the parents were aware of
acetate (DMPA). Although some authors have their daughters being sexually active. In Chile, pre-
expressed concern regarding the use of DMPA in scribing contraceptives to adolescents between 14
teens due to loss of bone mineral density (BMD), and 18 years old is permitted by the National Guide-
complete recovery of BMD occurs within 12 months lines on Fertility Regulation of the Ministry of Health,
of contraceptive discontinuation in teenagers.4,5 The without permission of the parents.7 Contraceptive pro-
World Health Organization (WHO) has recently rec- vision to women and men in this age group at the
ommended that use of DMPA should not be restricted Center was approved by the Ethics Committee of
in teenagers.6 The objective of this prospective obser- the Faculty of Medicine, University of Chile on Sep-
vation cohort, nonclinical trial study was to compare tember, 14, 2000, when the Chilean law changed, in-
two groups of hormonal contraceptive users under creasing the age of voluntary coitus from 12 to 14
19 years of age: one using a monthly combined estro- years old.7
gen-progestin injectable (IC) and the other using an All adolescents had the chance to be interviewed
oral contraceptive. All subjects were nulligravidas thoroughly and privately. PAP smear and ultrasound
preventing first pregnancy. examinations were performed as necessary. Blood
pressure was monitored by the physician using a mer-
Materials and Methods cury manometer and body weight taken by a trained
nurse using a SeccaÓ balance scale, calibrated every
The study was conducted at the Center for Adolescent day with a metal block of 1 kg. The body weight was
Reproductive Medicine, Faculty of Medicine, Univer- taken without shoes and with light dress. All informa-
sity of Chile in Santiago (CEMERA). Nulligravids tion was kept confidential. Participants received coun-
were adolescents from lower-middle and low income seling on human sexuality, contraception, sexually
levels, who had not previously used hormonal contra- transmitted infections, and HIV. IC, OC, and condoms
ception, except two that changed from OC to IC were provided at no charge. Information was regis-
because of intolerance during the recruitment period. tered on special files recording information related
Our team was staffed by trained specialists in pediat- to the family, mental health and gynecological as-
ric and adolescent gynecology, a social worker, pects. IC users returned for monthly injection because
psychiatrist, psychologist, family counselor, midwife, the facilities and free of charge at the Center. For
and nutritionist. visits, the IC and OC users returned every two to three
For this non-clinical trial study, recruitment months or at any time, if she needed consultation, al-
extended from September 1998 to March 2005. After ways free of charge. Follow-up by phone or home
receiving a detailed counseling and information about visits was not performed, so as to comply with strict
contraception, the decision whether to use IC or OC confidentiality.
was made by the adolescents: 206 adolescents The injectable selected was a combination of 50mg
requested injectables and 224 requested OCs. They norethisterone/5mg estradiol valerate. The oral con-
were not assigned by a random selection to IC or traceptive selected was a combination of 0.15 mg lev-
OC contraception, but those adolescents with risk fac- onorgestrel/0.03 mg ethinyl estradiol. Both methods
tors received a special counseling to use an injectable were donated by Schering of Chile and provided to
contraceptive. adolescents free of charge. There were no payment
However, many did not return to the clinic after or special incentives for professionals or other person-
receiving the first injection or OC package (82 and nel in this study.
97, respectively). Consequently, 124 subjects were The objective of the study was to analyze the effi-
followed in the IC group and 127 in the OC group, cacy, safety, acceptability and continuation rates of
involving 1044 and 1368 months of observation, re- a monthly injectable and an oral contraceptive.
spectively. At the end of the second month of observa- Data were continuously registered. Groups were
tion, 29 and 26 subjects in the IC and OC groups, compared using Pearson chi-square, odds ratio

3. Molina et al: Comparison of Injectable and Oral Contraceptives 27
(OR), and 95% confidence interval, t test and propor- One pregnancy occurred in the OC group with
tion difference test.8e10 a Pearl Index of 0.88. No pregnancies occurred in
the IC group.
The Center provides health services to young peo-
Results ple up to 19 years old. Beyond that age, they are re-
ferred to adult outpatient clinics within the Primary
As shown in Table 1, adolescents have more than one Heath Care System. This explains the discontinuation
risk factor. Social risk, absolute necessity of privacy of 0.81% of IC and 2.36% of OC group. Therefore,
to use contraception and psychiatric problems were real discontinuation rates were 58.10 % for IC and
significantly higher within the IC group users (OR: 62.24 % for OC, without including aging out, this last
5.4, 3.6 and 18.7 respectively) Adolescents at social administrative reason for discontinuation.
risk were those experiencing serious personal or fam-
ily problems, including troubles with the law or resid-
ing at special juvenile homes, where they were Discussion
referred to the Center by a juvenile court judge. Ado-
lescents with the need for absolute privacy to use con- Although this study was a 12-month study, new ado-
traceptives were those with an extreme lack of lescents are still being seen as part of daily clinical ac-
communication with their very traditional parents. tivities at the Center. At the beginning, adolescents
Psychiatric, neurological, and neurodevelopment dis- who choose the monthly IC were those with associ-
orders included depression, anorexia nervosa/bulimia, ated high risk factors. Clinical experience revealed
epilepsy, and one with low IQ. The IC subject with that many adolescents at low risk also asked for
80e90 IQ discontinued at 6 months of observation, monthly IC, encouraged by other clients of the Center
because of decision of the parents. IC users showed since this was a confidential method. On the last eval-
a greater proportion of alcohol and cocaine abuse, uation at 2007, out of the total new adolescent users at
and a higher number of sexual partners. the Center, 50% choose monthly injectables.
Other health characteristics and physical findings A study comparing a monthly combined injectable
were similar in both groups. At 3, 6, 9, and 12 months of 50 mg noresthisterone enanthate and IUD in pre-
of observation, no differences were found in IC and menopausal women showed no differences in spinal
OC users on normal change of blood pressure and bone density after two years of observation.11 Other
weight gain. The proportion of dysmenorrhea was sig- studies on hormonal replacement therapy with a com-
nificantly higher with IC at 3, 6, 9, and 12 months (Ta- bination of norethisterone acetate and estrogens have
ble 2). Although not shown in the table, breast shown an increase in bone mineral density.12e15
tenderness was also higher in IC users and signifi- However, there is no information regarding nore-
cantly higher at months 3 and 9. thisterone enanthate in adolescents. Available infor-
Regarding the menstrual cycle, the proportion of mation shows that low dose oral contraceptives
hypermenorrhea was higher in IC users at months 3 containing 0.02mg ethinyl estradiol have no effect
and 6, the incidence of hypomenorrhea was higher on bone resorption in young women. Gestodene is
in IC at all intervals. Amenorrhea was higher in the capable of reducing bone resorption.16
IC group, but with no significant differences. Spotting This study revealed that blood pressure and body
was also higher in IC at months 3, 6, and 9. From the weight were slightly higher but insignificantly, in
last line of the table it can be seen that irregularity of OC users and they remained within the normal range.
menstrual cycles on IC users, reached 35%, 21%, The difference in body weight was higher in OC users
19%, and 22% at months 3, 6, 9, and 12 of observa- at months 9 and 12 of observation; no body weight
tion, as compared to 4%, 4%, 0%, and 0% among changes were observed in IC users as previously
OC users at the same intervals. In summary: cycle dis- reported in a Colombian open study.17
turbances are higher in IC users. The incidence of dysmenorrhea, in two different
Table 3 shows the discontinuation rates. At month studies with monthly combined injectable of 50 mg
12, including all subjects with 3 or more months of noresthisterone enanthate, was 6.5% and 9.83 % re-
observation, rates were 58.9% and 64.6% for IC and spectively at month 12.18,19 In our study, the inci-
OC users, respectively. The difference (5.7%) was dence of dysmenorrhea reached 41% among IC
not significant (P O 0.05). Loss of follow-up was users and 14% among OC users at month 12. This
the main cause of discontinuation, followed by per- study showed a higher incidence of breast tenderness
sonal reasons and medical indications. There was (12% and 14%) at months 6 and 12 than the one re-
a significant difference between IC and OC at month ported by other investigators (1.1 % and 4%) for the
12, with higher and significant cycle disturbances in same periods of observation.18 The proportion of dys-
IC users. menorrhea and breast tenderness is higher in this

4. 28 Molina et al: Comparison of Injectable and Oral Contraceptives
Table 1. Risk Factors Associated with Contraceptive Choice
IC OC Total
Risk Factors N % N % N % Pe OR (95%)
Factors Detected
Yes 71 57.3 121 95.3 192 76.5 .0001 0.07 (0.02e017)
No 53 42.7 6 4.7 59 23.5
Social Risk
Yes 42 33.9 11 8.7 53 21.1 .0001 5.4 (2.5e11.9)
No 82 66.1 116 91.3 198 78.9
Absolute Privacy
Yes 32 25.8 11 8.7 43 17.1 .0001 3.67 (1.7e8.2)
No 92 74.2 116 91.3 208 82.9
Psychiatric Morbidity
Yes 16 12.9 1 0.8 17 6.8 .0001 18.7 (2.8e788.8)
No 108 87.1 126 99.2 234 93.2
Medical Morbidity
Yes 2 1.6 1 0.8 3 1.2 .61c 2.07 (0.1e122.8)
No 122 98.4 126 99.2 248 98.8
HOC Intolerance
Yes 2 1.6 0 0.0 2 0.8 .24c
No 122 98.4 127 100.0 249 99.2
Others
Yes 2 1.6 0 0.0 2 0.8 .24c
No 122 98.4 127 100.0 249 99.2
a
P value of corrected c2 test (**) 95% confident limitsdHOC: Hormonal oral contraceptives.
c
Not significant.
e
P significant ! .005.
study, because both mild and severe cases were preparation of 50 mg noresthisterone enanthate users
considered. the proportion of irregular bleeding was 33.3% and
In Phase III WHO clinical trials, irregular bleeding 20% for the same period of observation.20 In 38 ado-
in monthly combined injectable of 50 mg noresthis- lescents using the same monthly injectable contracep-
terone enanthate users over 18 years varied from tive and followed for one year, the abnormal bleeding
34.6% at 3 month of use to 14.6% at month 12.19 In was 26.2% and 28.9% at 3 and 12 months respec-
another recent study of monthly combined injectable tively.21 Our findings of irregular cycles was higher
Table 2. Menstrual Patterns and Irregular Cycles in Adolescent IC and OC users at 3, 6, 9 and 12 Months of Follow-up
3 months 6 months 9 months 12 months
Menstrual Pattern N % N % N % N % P*
Total cases observed 196 100.0 141 100.0 98 100.0 52 100.0 NS
Injectable contraceptive 95 48.5 70 49.6 43 43.9 23 44.2
Oral contraceptive 101 51.5 71 50.4 55 56.1 29 55.8
Hypermenorrhea 11 5.7 3 2.1 1 1.0 0 NS
IC 10 10.5 3 4.3 1 2.3 0
OC 1 1.0 0 0 0
Hypomenorrhea 9 4.6 6 4.3 3 3.1 3 5.8 NS
IC 8 8.4 5 7.1 3 6.9 3 13.0
OC 1 1.0 1 1.4 0 0
Amenorrhea 1 .5 0 1 1.02 1 1.9 NS
IC 1 1.1 0 1 2.3 1 4.3
OC 0 0 0 0
Spotting 16 8.2 9 6.4 3 3.1 1 1.9 NS
IC 14 14.7 7 10.0 3 6.9 1 4.3
OC 2 1.9 2 2.8 0 0
Regular cycles 159 81.1 123 87.2 80 81.6 47 90.3
IC 62 65.2 55 78.6 35 81.4 18 78.3 0.03
OC 97 96.0 68 95.8 55 100.0 29 100.0
a
P 5 Proportion Difference Test; *P # 0.05, NS 5 Not significant.

5. Molina et al: Comparison of Injectable and Oral Contraceptives 29
Table 3. Discontinuation rates by Reasons of IC and OC users at 3, 6, 9, and 12 Months of Follow-up
Total accumulative
3 months 6 months 9 months 12 months 1 e 12 months
Discontinuation Reasons n % n % n % n % n % P*
Pregnancy 1 0 0 0 1 ———
IC 0 0 0 0 0 0 0 0 0 0
OC 1 0.8 0 0 0 0 0 0 1 0.8
Personal Reasons 7 6 3 2 18 0.84
IC 3 2.4 3 3.1 2 2.7 1 1.6 9 7.3
OC 4 3.1 3 2.9 1 1.3 1 1.7 9 7.1
Cycle Disturbance 3 1 1 0 5 0.06
IC 3 2.4 1 1.0 1 1.4 0 0 5 4.0
OC 0 0 0 0 0 0 0 0 0 0
Breast 0 0 0 1 1 ———
Tenderness/Headache 0 0 0 0 0 0 1 1.6 1 0.8
IC 0 0 0 0 0 0 0 0 0 0
OC 0 0
Lost to Follow-up 35 37 18 16 106 0.46
IC 19 15.3 18 18.4 4 5.4 8 12.9 49 39.5
OC 16 12.6 19 18.6 14 18.2 8 13.8 57 44.9
Medical Indications 4 3 9 4 20 0.52
IC 1 0.8 1 1.0 5 6.8 1 1.6 8 6.5
OC 3 2.4 2 2.0 4 5.2 3 5.2 12 9.4
Over 19 years 1 2 0 1 4 0.63
IC 0 0 1 1.0 0 0 0 0 1 0.8
OC 1 0.8 1 1.0 0 0 1 1.7 3 2.4
Total Discontinuation 51 49 31 24 155 0.42
IC 26 21.0 24 24.5 12 16.2 11 17.7 73 58.9
OC 25 19.7 25 24.5 19 24.7 13 22.4 82 64.6
Total Continuation(**) 200 151 120 96 96 0.42
IC 98 79.0 74 59.7 62 50.0 51 41.1 51 41.1
OC 102 80.3 77 60.6 58 45.7 45 35.4 45 35.4
*P significant ! 0.05, corrected chi-square test (Total accumulative 1e12 months).
(**)
124 and 127 initial cases of IC and OC respectively.
at 3 months with 34.6% and lower at 21.7% at 12 the discontinuation rate was 48% at one year.21 In IC
months of observation in IC users, but significantly and OC groups, reasons for discontinuation were sim-
lower in OC users, with 4.0% and 0% of irregular cy- ilar to other studies with adult IC. Loss to follow
cles for the same period of observation. These finding up (39.5% and 44.9% for IC and OC users), was high-
with OC are very similar to those of untreated adults er in comparison with the adult studies, but similar
with contraceptives, where the irregular bleeding was to adolescent studies where the proportion was
4.5% and 8.6% at the 3 and 12 month of follow up.22 38.4%.17,18,21 This finding was expected, due to the
These findings confirm that bleeding irregularity im- well-known behavior of adolescents regarding contra-
proved with OC use, but it did not with IC use. ceptive use, especially of those who are preventing the
The higher irregular cycles of adolescent IC users first pregnancy.
might be related to the pubertal development stage There are differences in the continuation rates of
of this group, since 50% of users were under 16 years contraceptive users in clinical trials and regular clini-
and 11% of users under 14 years. It is generally ac- cal programs. In one study in the USA, with 5178
cepted that 43% of irregular cycles may occur during DMPA users, 57% returned for a second administra-
the first year after menarche. This percentage de- tion; 63% of those who returned for their second
creases to 20% after five years.23e25 Discontinuation injection went on to receive a third. The overall
rates at month 12 were 58.9% and 64.6% for IC and one-year continuation rate was 23%.26 In one other
OC users, respectively. In the Colombian and Latin study in Cairo, Egypt, nearly 70% of injectable users
American adult studies of monthly combined inject- had stopped using their chosen method after one year,
able of 50 mg noresthisterone enanthate discontinua- compared with 34% of IUD users and 10% of implant
tion rates were lower: 45.1 % and 17.9% at the end users.27 In the Philippines the continuation rates of
of the first year respectively, varying from 9.7% to contraceptive users were compared by quality of care.
49.5% among the six participating countries in the With low-quality, the discontinuation of use was
last study.17,18 In the study of 73 adolescents IC users 45%, with medium-quality it was 38%, and with

6. 30 Molina et al: Comparison of Injectable and Oral Contraceptives
high-quality it was 23 %.28 Based on Demographic ´
8. Canavos GC: Probabilidades y Estadıstica: Aplicaciones y
and Health Survey in six countries, the cumulative ´
Metodos. Editores McGraw-Hill/Interamericana 1988;
12-month probabilities of discontinuation per 100 333e8, 350.
episodes of method use, by country and by Pill ´ ´
9. Siegel S: Estadıstica No Parametrica: Aplicada a las
´
ciencias de la conducta. Mexico, Editores Trillas 1970;
and Other Modern Method were: Morocco: 35,1
130e7
and 49,8 ; Tunisia: 32,2 and 41,4 ; Egypt: 36,5 and ´
10. Martinez Oliva L: Cancer y ambiente. Bases epidemiolog- ´
58,7 ; Ecuador: 37,0 and 62,4; respectively. In Indone- ´ ´
icas para su investigacion y control: Metodos epidemiolo- ´
sia: 26,2 and 24,9 for pills and injectable. In Thailand: ´
gicos. Mexico, Editores Metepec, 1990; 57e59.
36,2 and 36,6 for pills and injectable.29 11. Kessuru E, Etchepareborda JJ, Wikinski R, et al: Premeno-
After analysis of 11 studies that assessed programs pause contraception with monthly injectable Mesigyna
in the USA, and that assessed policies were found. with special emphasis on serum lipid and bone density pat-
The intervention generally had positive albeit short- tern. Contraception 2000; 61:317
term effects on contraceptive use; none reduced 12. Arabi A, Garnero P, Porcher R, et al: Changes in body
pregnancy rates. Programs that gave women a contra- composition during postmenopausal hormone therapy:
ceptive during the visit were the most effective at a 2 year prospective study. Hum Reprod 2003; 18:1747
13. Rubinacci A, Peruzzi E, Modena AB, et al: Effect of low
increasing method use. Advance provision of emer-
dose transdermal E2/NETA on the reduction of postmeno-
gency contraception increased the likelihood of its pausal bone loss in women. Menopause 2003; 10:241
use and did not affect regular contraceptive use.30 14. Bunyavejchevin S, Limpaphayom KK: The metabolic and
Continuation rates at month 12 were 41.9% and bone density effects of continuous combined 17 beta estra-
37.8% for IC and OC, respectively, for those adoles- diol and norethisterone acetate treatments in Thai post-
cents 19 years old and less. Beyond that age, they menopausal women: a double-blind placebo-controlled
are referred to adult outpatient clinics within the Pri- trial. J Med Assoc Thai 2001; 84:45
mary Health Care System. 15. Delmas PD, Confavreux E, Garnero P, et al: A combina-
We can finally conclude that the ‘‘monthly inject- tion of low doses of 17 beta-estradiol and northisterone ac-
able’’ is one other contraceptive option for adoles- etate prevent bone loss and normalizes bone turnover in
cents seeking to prevent their first pregnancy and it postmenopausal women. Osteoporos Int 2000; 11:177
16. Paoletti AM, Orru M, Floris S, et al: Evidence that treat-
is particularly attractive for those facing psychosocial
ment with monophasic oral contraceptive formulations
risk factors and higher possibilities of contraceptive containing ethinylestradiol plus gestodene reduces bone
use discontinuation. resorption in young women. Contraception 2000; 61:259
˜
17. Gomez PI, Correa JE, Castaneda A, et al: Estudio abierto
Acknowledgments: The authors wish to thank Schering of Chile ´
multicentrico del anticonceptivo inyectable mensual. Con-
for the donation of the monthly injectable contraceptives. ´
troversias en Ginecologıa y Obstetricia 1998; 6:6
18. Bassol S, Cravioto MC, Durand M, et al: Mesigyna once-
a-month combined injectable contraceptive: experience in
References Latin America. Contraception 2000; 61:309
19. Fraser IS: Vaginal bleeding patterns in women using one-
1. Nelson ML, Quintana SM: Qualitative clinical research a-month injectable contraceptives. Contraception 1994;
with children and adolescents. J Clin Child Adolesc Psy- 49:399
chol 2005; 34:344 20. Bulent Tiras M, Noyan V, Fener N, et al: Effects of
´
2. Molina R: Anticoncepcion en la adolescencia. In: a monthly injectable steroidal contraceptive, Mesigyna,
´
Molina R, Sandoval J, Gonzalez E, editors. Salud Sexual on menstrual pattern, lipoproteins, and coagulation param-
y Reproductiva en la Adolescencia. Santiago, Chile, Med- eters. Contraception 2001; 63:151
´
iterraneo, 2002, pp 768e785 21. Bortolotti de Mello Jacobucci MS, Guazzelli CA,
3. Morgan Mulchahey K: Practical approaches to prescribing Barbieri M, et al: Bleeding patterns of adolescents using
contraception in the office setting. Contraception 2005; 16: a combination contraceptive injection for 1 year. Contra-
665 ception 2006; 73:594
4. Tremollieres F: [Effect of hormonal contraception on bone 22. Belsey EM: and Task Force on Long-acting Systemic
mineral density.] Gynecol Obstet Fertil 2005; 33:520 Agents for Fertility Regulation: Menstrual bleeding pat-
5. Scholes D, Lacroix AZ, Ichikawa LE, et al: The associa- terns in untreated women and with long-acting methods
tion between depot medroxyprogesterone acetate contra- of contraception. Adv Contracept 1991; 7:257
ception and bone mineral density in adolescent women. 23. Widholm O, Kantero RL: A statistical analysis of the men-
Contraception 2004; 69:99 strual patterns of 8,000 Finnish girls and their mothers. Ac-
6. World Health Organization: WHO statement on hormonal ta Obstet Gynecol Scand Suppl 1971; 14(Suppl 14):1
contraception and bone health. Contraception 2006; 73: 24. World Health Organization: Multicenter Study on Men-
443 strual and Ovulatory Patterns in Adolescent Girls. I. A
´ ´
7. Casas L: Confidencialidad de la informacion medica, der- Multicenter Cross-sectional Study of Menarche. World
echo a la salud y consentimiento sexual de los adoles- Health Organization Task Force on Adolescent Reproduc-
centes. Rev Chil Obstet Ginecol Inf Adolesc 2005; 2:94 tive Health. J Adolesc Health Care 1986; 7:229

7. Molina et al: Comparison of Injectable and Oral Contraceptives 31
25. World Health Organization: Multicenter Study on Men- from a longitudinal study in Cairo,. Egypt. Int Fam Plann
strual and Ovulatory Patterns in Adolescent Girls. II. Lon- Persp 2005; 31:15
gitudinal Study of Menstrual Patterns in the eaRly 28. RamaRao S, Lacuesta M, Costello M, et al: The link be-
Postmenarcheal Period, Duration of Bleeding Episodes, tween quality of care and contraceptive use. Int Fam Plann
and Menstrual Cycles. World Health Organization Task Persp 2003; 29:76
Force on Adolescent Reproductive Health. J Adolesc 29. Ali M, Cleland J: Contraceptive discontinuation in six
Health Care 1986; 7:236 developing countries: a cause-specific analysis. Int Fam
26. Westfall JM, Main DS, Barnard L: Continuation rates Plann Persp 1995; 21:92
among injectable contraceptive users. Fam Plann Perspect 30. Kirby D: The impact of programs to increase contraceptive
1996; 28:275 use among adult women: A review of experimental and
27. Tolley E, Loza S, Kafafi L, et al: The impact of menstrual quasi-experimental studies. Perspect Sex Reprod Health
side effects on contraceptive discontinuation: Findings 2008; 40:34