Contraception and the prevention of sexually transmitted diseases

Sexually transmitted diseases (STDs) are a major cause of ill health in women and their sexual partners and children. Contraceptive methods alter in various ways the risk of acquiring STD but assessment of the odds ratio is difficult due to the many confounding factors. Spermicides have been reported to kill a wide range of bacteria and viruses including HIV in vitro and to protect in vivo from infection by gonorrhoea, chlamydia and pelvic inflammatory disease (organisms unspecified). Spermicides will not cure pre-existing infections. Condoms and diaphragms will give some protection from bacterial and viral infections in all parts of the genital tract. Hormonal contraception and tubal ligation give protection to the upper genital tract but not the cervix. Carcinoma of the cervix follows the same pattern as STDs. The risk of pelvic infection in intrauterine device users is discussed in the chapter by Bromham (pp 100-123, this issue).

Risk factors for urinary tract infection

The authors carried out a case-control study in 1982-1983 to investigate the possible influence of behavioral factors on the risk of urinary tract infection. Study participants were college women attending a student health service. Cases were 43 women with culture-confirmed urinary tract infection. There were two control groups: 149 women with upper respiratory infection and 227 women visiting the gynecology clinic. Using each set of controls, the study confirmed that sexual intercourse is a risk factor and that there is a dose-response effect for increasing levels of coital frequency. The study also found that use of the diaphragm was significantly associated with urinary tract infection (odds ratios 3.0, 2.3), an association which remained significant even after controlling for possible confounding by coital frequency. The findings did not show an association with many of the factors commonly believed to be important such as type of clothing worn and volume of fluids consumed.

Urinary tract infection in relation to diaphragm use and obesity

We have examined factors influencing the rate of first referral to hospital for urinary tract infection among the 17,032 women taking part in the Oxford Family Planning Association contraceptive study. The risk of first referral declined with age, was higher in nulliparous women than in parous women, was higher in non-obese than in obese women and was higher in current users of the diaphragm than in current users of other methods or no method of contraception. The main increase in the risk of referral in current diaphragm users occurred during the first 24 months when overall rates were 2-3 times higher in users than in non-users or ex-users of the diaphragm. The negative association between hospital referral for urinary tract infection and obesity was unexpected. It was not explicable in terms of age, parity or diaphragm use. It may be that obese women are less likely to receive trauma to the genital area during sexual intercourse than non-obese women because adipose tissue offers them some protection. Another possibility is that increased oestrogenization in obese women, resulting from peripheral conversion of androstenedione to oestrone, has a beneficial effect on the bladder and urethra, thus reducing the liability to infection.

Association between diaphragm use and asymptomatic bacteriuria

The prevalence of asymptomatic bacteriuria was assessed in women using different contraceptive methods. Three hundred and twenty women attending a family planning centre were studied, 80 in each of the following groups: diaphragms, intrauterine contraceptive devices (IUCDs), oral contraceptives (OCs) and no contraception. The numbers with asymptomatic bacteriuria in the 4 groups were as follows: diaphragm - 12 (all E coli); IUCD - 3 (E coli; P mirabilis; S saprophyticus); OC - 5 (all E coli); no contraception - 4 (3 E coli; 1 S saprophyticus). The prevalence of Gram-negative bacteriuria in women using diaphragms was significantly higher than for women in the other groups (chi 2 = 8.98; p less than 0.05). Factors such as parity, numbers of sexual partners and frequency of sexual intercourse had no apparent effect. The use of diaphragms may contribute to the risk of Gram-negative urinary tract infections in sexually active women.

Oral contraception and serious psychiatric illness: absence of an association

The incidence of serious psychiatric illness, as measured by first referral to hospital for specialist advice and treatment, has been investigated among 16,746 women taking part in the Oxford Family Planning Association contraceptive study. Of these women, 9,504 were recruited while using oral contraceptives, 4,144 while using a diaphragm and 3,098 while using an intrauterine device. The results are reassuring with respect to oral contraceptive use. First referral rates per 1000 woman-years of observation in the oral contraceptive, diaphragm, and intrauterine device entry groups were 3.0, 2.6, and 2.8 respectively for non-psychotic psychiatric disorders and 0.46, 0.43 and 0.53 respectively for psychotic disorders. Attempted suicide occurred only 40% as often amongst diaphragm users as amongst users of oral contraceptives or intrauterine devices; this finding presumably reflects the characteristics of women who choose the diaphragm as their birth control method.

Relationship between contraceptive method and vaginal flora

This study was undertaken to assess whether the vaginal flora was affected by the method of contraception, and in particular as to whether the incidence of vaginal candidiasis increased when oral contraceptives were used. One thousand and two consecutive vaginal or cervical swabs from women attending a family planning centre were cultured. Candida albicans was isolated from 13% of women using no contraception, 16% using oral contraceptives, and from 9%, 19% and 18% of those using diaphragms, intrauterine contraceptive devices (IUCD) and condoms respectively. These differences were not statistically significant. Women using an IUCD had significantly more Gram-positive cocci cultured than women in any other group, while those using diaphragms had significantly more Gram-negative bacilli. Our clinical impression that the use of oral contraceptives led to an increase in vaginal candidiasis, was not confirmed by this study.

Toxic shock syndrome and diaphragm use

A case of toxic shock syndrome (TSS) associated with diaphragm use is presented. Adolescents who use a diaphragm should be informed of the symptoms of TSS, and those with the syndrome should be questioned about diaphragm use.

The effects of prolonged retention of diaphragms on colonization by Staphylococcus aureus of the lower genital tract

To determine whether prolonged retention of diaphragms alters Staphylococcus aureus colonization of the lower genital tract, 183 nonpregnant, asymptomatic women were screened for the presence of this pathogen in the cervix and upper vagina. Nineteen (10.4%) had positive cultures: 5 from the vagina, 8 from the cervix, and 6 from both sites. A second examination with quantitation revealed the presence of S. aureus in 7 of the 19 patients. In five of the six available patients, the number of staphylococci increased significantly after prolonged (24 hour) retention of diaphragms and decreased in one subject only. In two additional patients S. aureus was recovered after, but not before, the use of diaphragms. An increase in the number of other microorganisms also was noted after prolonged retention of diaphragms. In vitro study of the spermicide nonoxynol-9 revealed that it had no inhibitory activity on staphylococci or group B streptococci but was highly effective against Streptococcus pneumoniae.