Infertility is defined as the inability for a couple having regular unprotected sexual intercourse to have a baby. Globally, the rate of fertility is declining but infertility still affects one in seven couples in New Zealand. In general, humans are generally not considered to be an especially fertile species, with a potential capability of 20-30% reproductive success with each menstrual cycle, albeit in a small window of opportunity for fertilisation of 5-6 days within each menstrual cycle. Fertility is highest in women in their 20s, and the rate of fertility declines with age, declining even more rapidly in a woman’s 40s, until the age of 50 where menopause occurs. This is when all of a woman’s eggs are exhausted within the ovaries and reproductive capacity ceases.

Women are increasingly delaying childbearing usually due to social and economic reasons. This, coupled with a gradual decline in fertility, means that other causes of infertility can become a significant issue, including having lifestyle factors such as obesity and smoking and sexually transmitted infections such as chlamydia and gonorrhea. These infections are further complicated by the fact that carriers of these infections can remain symptomless.

Chlamydia: the tip of the infertility iceberg
Chlamydia is the most common sexually transmitted infection in New Zealand, caused by the bacterium Chlamydia trachomatis. Chlamydia can be transmitted during vaginal, anal, or oral sex, and can be passed from an infected mother to her baby during childbirth. Chlamydia infections do not exhibit any symptoms in approximately 70% of women and 25% of men. While a chlamydia infection can be effectively cured with antibiotics, if left untreated there can be serious long-term reproductive consequences.

Approximately half of the women with a symptomless chlamydia infection will develop pelvic inflammatory disease, which is a generic term for infection of the uterus, fallopian tubes, ovaries and its surrounding tissues. Pelvic inflammatory disease can result in scarring and permanent damage of the reproductive organs, which can cause serious complications such as chronic pelvic pain, ectopic pregnancies (when an embryo implants in other parts of the female reproductive tract apart from the uterus), and infertility, especially with repeat infections. In men, if left untreated, chlamydia can cause pain, swelling and inflammation in the testes and urethra, and also lead to infertility.

According to a recent report to the Ministry of Health, laboratory surveillance efforts by the Institute of Environmental Science and Research Limited (ESR) showed that chlamydia was the most commonly reported sexually transmitted infection in 2014. With a national rate of 629 cases per 100,000 population, our rates are double those of Australia and the UK. 83% of cases reported were aged between 15 and 29 years. Chlamydia rates for males increased by 24.9% in the 40 years and over age group, and increased by 10% in the 25–29 years age group, but were generally stable in all other age groups. Chlamydia rates decreased in all age groups for females. However, there was more than twice the number of cases of chlamydia in women than in men. The national rate for females was 869 per 100,000 population (19,986 cases) compared to males that was 375 per 100,000 population (8275 cases).

Gonorrhoea: not quite the round of applause you’d like…
Gonorrhoea (commonly known as the clap) is a sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae, that can be transmitted during vaginal, anal, and oral sex, and from an infected mother to her baby during childbirth. The usual symptoms in men are a burning sensation when urinating and penile discharge. Women, on the other hand, may have vaginal discharge and pelvic pain. Gonorrhoea infections do not exhibit any symptoms in approximately 50% of women and up to 5% of men. If left untreated, the infection can spread locally, causing inflammation in the testes in men, or pelvic inflammatory disease in women. Gonorrhoea can also spread to affect joints and heart valves in the body.

According to the ESR survey, in 2014 our national gonorrhoea rate was 70 cases per 100,000 population, with 73% of those cases being in people aged between 15 and 29 years. The national rate for males was 77 per 100,000 population (1633 cases) and was higher than the national rate for females, that was 62 per 100,000 population (1367 cases). Between 2010 to 2014, there have been increasing rates of gonorrhea in both men and women, in a number of age groups; 40 years and over, and 25–29 years in men, and 15– 19 years and 30–34 years, in women. In this same time period, the numbers of gonorrhoea cases reported in women were highest in the 15–19 years and 20–24 years age groups, and in men were highest in the 25–29 years age group. More concerning is that antibiotic-resistant strains of N. gonorrhoeae have been identified in gonorrhea patients in New Zealand.

Reproductive health is an easily forgotten and underrated area of personal health care. Early recognition and effective treatment of sexually transmitted infections is an important protection against later problems with declining human fertility.



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Dr Anita Muthukaruppan is a breast cancer researcher with the Department of Obstetrics and Gynaecology at the University of Auckland. She is a science geek with interests in gynaecological cancers, infertility, pregnancy, sexually transmitted infections, antibiotics, vaccines, carnivorous plants and quantum physics. Shea also loves Sir David Attenborough, Professor Stephen Hawking and Dr Emmett Brown.

Professor Andrew Shelling is Associate Dean (Research) at the Faculty of Medical and Health Sciences, and also head of the Medical Genetics Research Group in the Department of Obstetrics and Gynaecology. His research is primarily interested in understanding the molecular changes that occur during the development of genetic disorders, focusing on breast and ovarian cancer, and reproductive disorders. Andrew enjoys trying to keep up with advances in science.

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