 |
| Image in the public domain, courtesy of Wikimedia Commons |
2010 saw the 50th anniversary of the
contraceptive pill.
‘The pill’ as it is commonly known was a key player in
building women’s current economic role in society as it gave women an
unprecedented control over their own fertility.
Oral contraceptives remain the most common method of
contraception in most part of the world. According to a CDC Faststats:
- Leading contraceptive method among women aged 15-29: Pill
- Percent of women aged 15-44 currently using the pill: 17.1%
Although the failure rate is 0.1 percent when pills are
taken perfectly (same time every day, no missed pills), the actual failure rate
is 9 percent over the first year, due primarily to the missed pills, drug
interactions, forgetting to restart the pill after the seven-day pill-free
interval or illness and results in what is known as breakthrough pregnancy.
 |
photo courtesy: http://www.catholicmatch.com
|
Studies conducted in the past with high dose preparations
have linked various birth defects with first trimester exposure to oral
contraceptives. These birth defects involved the vertebrae, anus, heart,
trachea, esophagus, kidney and limbs (VACTERL syndrome) (Nora et al, 1976).
After thorough
investigation in the later years, these associations have not been
substantiated. These studies were mainly focused on use of the OC during the
first trimester. No studies were found
that studied the effect of exogenous hormones immediately before and around the
time of conception or immediately after conception.
This prospective observational cohort study conducted by Brittany M Charlton from the Department of Epidemiology,
Harvard T. H. Chan School of Public Health, Boston, Massachusetts and her colleagues from Denmark was published on line on January 6,
2016 in British Medical Journal and aims to study the association between use
of oral contraceptives around pregnancy time and resulting congenital
malformations in the fetus.
They used Medical Birth Register records from 1997 to 2011
(880,694 live births) and Danish National Prescription Register and collected
prescription data on the use of oral contraceptives. The investigators assumed
that women who filled their prescriptions were exposed to oral contraceptives.
The women were divided into 4 groups, No oral contraceptive
exposure, >3 months before pregnancy onset (reference group), 0-3 months
before pregnancy onset (that is, recent use), and after conception. The two
primary exposures of interest were after conception and recent use before
pregnancy onset.
Any major birth defect was the primary outcome and subgroups
of major birth defects categorized by organ system were the secondary outcomes.
Previous studies have observed associations between oral
contraceptive exposure and 4 subgroups of congenital anomalies of hypoplastic
left heart syndrome, gastroschisis, limb defects, and urinary tract anomalies.
Logistic regression was used to o estimate prevalence odds
ratios of any major birth defect as well as categories of birth defect
subgroups.
It was seen that the prevalence of major birth defect was
consistent at 25 per 1000 live births across all the four groups. The study did
not find any increase in the 4 birth defects that earlier studies have shown a
link with.
The study lacked the statistical power for different
formulations of oral contraceptives and specific subgroup of birth defects, but
was very strong when it comes to examining the association between birth
defects and the timing of oral contraceptives use.
It also stands at par with other studies conducted earlier,
documenting no increase in birth defects after the use of oral contraceptives.
It also assures the patients and healthcare providers about
no association between the oral contraceptive use and increased risks of
malformation, as estimated 9% of oral contraceptive users become pregnant in
the first year of use; many more women will stop using oral contraceptives when
planning a pregnancy and conceive within a few menstrual cycles.
The study also postulate that future research could examine
the different formulations of oral contraceptives as other health outcomes,
such as breast cancer risk have varied by formulation—with triphasic
levonorgestrel formulations driving the increased breast cancer risk.
References:
Mosher WD, Jones J.
Use of contraception in the United
States: 1982-2008. Vital Health Stat 23 2010:1-44.
Skouby SO.
Contraceptive use and behavior in the 21st century: a comprehensive study
across five European countries. Eur
J Contracept Reprod Health Care 2004;9:57-68.
No comments:
Post a Comment