Patterns of contraception in IDDM in the UK RA Lawrenson, GM Leydon, TJ Williams, RB Newson, MD Feher* Department of Epidemiology and Public Health, *Department of Clinical Pharmacology Imperial College School of Medicine

Contraception in women with IDDM No UK studies No comparative studies Important to prevent unwanted pregnancies Risks of contraceptive use may have more serious consequencies in women with IDDM

Oral contraceptive use Commonest method used in the UK Combined oral contraceptives with high doses of oestrogen may increase risk of cardiovascular disease and increase requirement for insulin CHD risk may be due to changes in lipids. New generation oral contarceptives (gestodene and desogestrel) seem to increase HDL and decrease LDL

Oral contraceptive use (POPs) Progestogen only pills have less risk of cardiovascular problems. However they are less effective with 3 pregnancies per 100 women years of use Also have the problem of irregular bleeding

Percentage of women by age using combined oral contraceptives for contraception

Percentage of women by age using third generation combined oral contraceptives

Percentage of women by age using second generation combined oral contraceptives

Preferential prescribing of third generation oral contraceptives ? Proportion of women with IDDM using a third generation oral contraceptive was 60% compared with 58% in women with no diabetes - OR 1.06 which was not statistically significant.

Percentage of women by age using oral progestogen preparations for contraception

Percentage of women by age using injectable progestogen preparations for contraception

Percentage of women by age using diannette progestogen preparations for contraception

Comparison of different hormonal contraception usage in women with IDDM and women without diabetes in 1994

Summary of use of oral contraceptives in women with IDDM Women with IDDM are less likely to be prescribed an oral contraceptive If they are prescribed an oral contraceptive it is most likely to be a combined oral contraceptive Women with IDDM are twice as likely to be prescribed a POP There is no evidence of preferential prescribing of third generation COCs to women with IDDM in 1994

IUCD IUCD use has been associted with increased risk of pelvic inflammatory disease One series in 30 women with diabetes resulted in 11 pregnancies in the first year (contradicted by other studies)

Percentage of women by age using an intra uterine device for contraception

IUCD summary 2.9% use in women with IDDM and 2.2% in those with no diabetes - adjusted OR 1.21 (0.80,1.82) No evidence that it is being avoided as a method in women with IDDM

Barrier methods Under reporting on GP records Diaphragm or cap 0.8% in women with IDDM and 0.4 in comparison group adjusted OR 1.64 (0.72,3.74) Condom use 0.3% in IDDM and 0.9% in others adjusted OR 0.32 (0.10,1.02)

Percentage of women by age with a prescription for condoms

Surgery May be under recording of hysterectomy and sterilisation No information of vasectomy in partners In high risk women with IDDM pregnancy maybe such a risk that sterilisation is recommended (Steel)

Proportion of women by age with a record of sterilisation prior to 1995

Proportion of women by age with a record of a hysterectomy prior to 1995

Use of sterilisation 5.8% women with IDDM had a record of sterilisation compared with 3.7% of others. adjusted OR 1.32 (0.98,1.79) Hysterectomy rate was 3.8% vs 3.7% which after adjustment gave an OR of 0.91 (0.63,1.30) Some evidence of an increased use of sterilisation in women with IDDM

Confounding variable Age Sexual activity Smoking Obesity Hypertension

Age

Sexual activity

Proportion of women by age in whom there is a record of a claim from the GP for contraceptive services in 1994

Evidence of a cervical smear in 1992, 1993 or 1994 - women with IDDM and women with no diabetes

Smoking

Proportion of women recorded as being current smokers in 1994 by age

Proportion of women recorded as being ex-smokers in 1994 by age

Smoking 20.4% of women with IDDM and 20.2% without were recorded as being current smokers More emphasis should be put on this risk factor for women with IDDM

Obesity Obese women have an increased risk of CVD and should therefore be less likely to be prescribed combined oral contraceptives

Proportion of women in each BMI category (1 = <20, 2 = 20-25, 3 = 25-30, 4 = 30-35, 5 = 35+)

Obesity The mean BMI of women with IDDM was 26.2 (95% CI 25.4,26.9) Mean BMI in women without diabetes was 24.1 (24.0,24.2) Differences in the two groups suggest that this should be adjusted for in the analysis

Hypertension Record of a diagnosis of hypertension linked to a prescription in 1994 17/938 (1.8%) women with IDDM and 54/10,000 (0.5%) women without diabetes were being treated for hyertension Not statistically different

Pregnancy Increased risk to mother with IDDM Increased risk of abnormality in the baby

Risk of pregnancy by age group IDDM vs no diabetes in 1994 Overall RR 0.77 (.59,1.02)

Proportion of women with a record of a pregnancy in 1994 by age

Use of oral contraceptives in women with IDDM from different countries

Use of progestogen only pills in women with IDDM from different countries

Use of IUCD in women with IDDM from different countries

Use of female sterilisation in women with IDDM from different countries

Use of vasectomy in the partners of women with IDDM from different countries

Use of barrier methods of contraception in women with IDDM from different countries

Conclusions