Maternal use of oral contraceptives and risk of birth defects in Denmark: prospective, nationwide cohort studyBMJ 2016; 352 doi: https://doi.org/10.1136/bmj.h6712 (Published 06 January 2016) Cite this as: BMJ 2016;352:h6712
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Early pregnancy scans diagnose underestimated birth defects Re: Maternal use of oral contraceptives and risk of birth defects in Denmark: prospective, nationwide cohort study
Charlton and colleagues found that oral contraceptive exposure before or during pregnancy did not increase the risk of major birth defects among 880 694 live births between 1997 and 2011 in Denmark.1 Importantly the number of foetal abnormalities detected in early terminated pregnancies was not included which means many major congenital abnormalities would be missed.2
In 1976 the Oxford/FPA contraception study found “a surprisingly low incidence” of congenital abnormalities among live infants born to nulliparous women who had never taken hormonal contraceptives compared with nulliparous ever users (0.4% compared with 3.8%).3 The particularly high incidence of spina bifida between 1964 and 1972 was attributed to the use of hormonal pregnancy tests involving taking large doses of oral contraceptive progestogens and oestrogens.4
Since then, scans in early pregnancy have increased early terminations of an unknown number of abnormal foetuses. The “morning after” emergency contraceptive pills also contain large doses of a progestogen which is potentially teratogenic.5-7 Congenital anomalies developing in any surviving foetuses, who are later aborted, are not usually recorded with prescription records.
Use of hormones before or during pregnancy increases the likelihood of essential nutrient deficiencies or imbalances which are also major causes of teratogenesis and poor health in children.8
It is difficult to believe that use of contraceptive progestogens and oestrogens protects the ovary because use of identical or similar hormones for less than five years as hormonal therapy causes ovarian cancer and risks increase with longer use.9 Progestogens can also cause ovarian cancer in animals.10
A major congenital anomaly affects 2-3% of newborn babies. Congenital anomalies are an important cause of fetal, neonatal, and child mortality and morbidity, accounted for 21% of perinatal and infant deaths in the United Kingdom in 2001.2
1 Charlton BM, Mølgaard-Nielsen D, Svanström H, Wohlfahrt J, Pasternak B, Melbye M. Maternal use of oral contraceptives and risk of birth defects in Denmark: prospective, nationwide cohort study BMJ 2016;352:h6712.
2 Boyd PA, Armstrong B, Dolk H, et al. Congenital anomaly surveillance in England - ascertainment deficiencies in the national system. BMJ 2005; 330:27-29.
3 Vessey MP, Doll R, Peto R, et al. A long-term follow-up study of women using different methods of contraception. Br J Obstet Gynae 1976; 8: 373-424.
4 Gal I, et al. Hormonal pregnancy tests and congenital abnormalities. Nature 1967; 216: 83.
5 Murthy BKP, Prema K. Sister-cromatid exchanges in oral contraceptive users. Mutation Research 1979: 68:149-52.
6 Biri A, Civelek E, Karahalil B, Sardas S. Assessment of DNA damage in women using oral contraceptives. Mutat Res. 2002; 521: 113-9.
7 Lejeune J, Prieur M. Oral contraceptives and trisomy 21. A retrospective study of 730 cases. Annals of Genetics 1979: 22:61-66.
8 Grant ECG. The pill, hormone replacement therapy, vascular and mood over-reactivity, and mineral imbalance .J Nutr Environ Med 1998;8:105-116
9 Collaborative Group on Epidemiological Studies of Ovarian Cancer. Menopausal hormone use and ovarian cancer risk. Individual participant meta-analysis of 52 epidemiological studies. Lancet 2015; February 12.
10 Lipschutz A, Inglesias R, Pamosevick V, Salinas S. Ovarian tumours and other ovarian changes induced in mice by two 19-nor contraceptives. Br J Cancer 1967; 21: 153-157.
Competing interests: No competing interests
Oral contraceptive use preserves ovarian follicles intact, not only by preventing the creation of dominant fertile ones, but also by impeding atresic losses of numerous nearby follicles each month.
Women who use OCs for years, maintain their ovarian reserve unimpaired.
Later on, when they decide to pursue a pregnancy, their dominant follicle will not have to grow amidst an ocean of avascular atresia.
Expansion and maturation will take place in an optimal environment.
Quality of habitat, most advantageous setting, future conception, and children born this way, could manifest long term health benefits.
I urge the Authors of this excellent research study to monitor and compare these children after 5 and 10 years, considering prevalences for allergies, depression, sleep problems, learning difficulties, other common health issues.
Long term follow up is essential.
Competing interests: No competing interests