Rates and STI's

Over the past two decades England & Wales have been experiencing total fertility rates (TFR) lower than the necessary value for replacement of generations. At the same time new cases of sexually transmitted infections (STI) reported by Genito-urinary medicine (GUM) clinics have been steadily increasing. This case aimed to analyse the potential relationship between decreasing fertility rates in England & Wales and the number of new cases of STI's reported by GUM clinics.

Using raw data from the Annual abstract of statistics and the Department of health & social security, TFR between 1951-98 were calculated and correlated, using SPSS, with the total number of new cases of STI's. As a result a significant relationship between TFR & STI's was found. It finishes by explaining the relationship between fertility rates and STI's and looks at other, perhaps more influential factors affecting fertility rates, e.g. the introduction of the contraceptive pill, and the more recent trend in England and Wales towards later childbearing.

Europe is currently experiencing it lowest ever fertility levels and its longest ever period of fertility below replacement levels (Day 1995). By mid-1998 England & Wales TFR's less than 2.1 children per women for the best part of two decades (Table 1), well below the necessary value for replacement of generations (United Nations 1998). It may be that low fertility rates may just be postponement of births, e.g. more women are giving birth in their early forties (Ruddock et al 1998), or it could be the unavoidable end stage of full demographic transition i.e. populations that have full control over their fertility have better things to do than replace themselves (Day 1995) best plagiarism checker.

Whilst fertility rates within England and Wales have been decreasing, cases of STI's seen in GUM clinics have been steadily increasing. Between 1991 and 2001 reported cases of STI's in GUM clinics more than doubled in England & Wales (Figure 1) (www.statistics.gov.uk). Table 1. Age specific fertility rates, England 1960-94 (Hinde 2003) The aim of this case study was to statistically analyse the potential relationship between decreasing fertility rates in England & Wales and the number of new cases of STI's reported by GUM clinics. Therefore the null hypothesis Ho predicted that there was no relationship between decreasing fertility rates in England & Wales and the increase in number of STI's seen by GUM clinics.

Figure 1. From www.statistics.gov.uk, (The health of children & young people, Adolescent sexual health, March 2004) Using raw population data selected from the annual abstract of statistics, standard birth and fertility rates were calculated between 1951 and 1998 and compared with the number of cases of STI's reported in England between 1959 and 1993. Total fertility rates found in the literature confirm the calculated TFR's in this study. A small rise after the War, associated with demobilisation is then followed by a more sustained increase between 1958 & 1971, reaching a maximum of 2.89 in 1964. TFR then dramatically declines from 1971 to a record low of 1.66 in 1977. A slight increase occurred and from about 1980 TFR has remained relatively consistent at around 1.8 (Hine 2003).

Unfortunately data for the total number of STI's reported by GUM clinics in England & Wales were not available and for the purpose of this study data for England were assumed as representative of both England & Wales. Data for the total number of STI's reported by GUM clinics between 1951-98 in England is incomplete, however statistics for 1949 and 1959 were available and a line of best fit was fitted to the graph (Figure 6). Figure 6. Number of STI's reported by GUM clinics, England, 1949-1993

Between 1949 and 1993 new cases of STI's reported by GUM clinics in England increased by approximately 650%, from 110,900 in 1949 to 661,300 in 1993. In 2001 this figure stood at around 1,300,000 (Figure 1), a further increase of 200% since the beginning of 1990. Cases of Gonorrhoea and Chlamydia steadily increased between 1949 and 1986, which is significant as both, if untreated, are associated with pelvic inflammatory disease and tubal factor infertility (PHLS et al 2002). Cases of Gonorrhoea increased from 23,123 in 1949 to its peak of 58,734 in 1977, an increase of 254%. After 1977 we see a gradual decline in cases of Gonorrhoea (Figure 7).

Chlamydia likewise steadily increased from 21,492 in 1959 to its peak in 1986 of 157,792, an increase of 734%. Similar to Gonorrhoea, cases of Chlamydia declined between 1986 and 1993 (Figure 8). Figure 7. New cases of Gonorrhoea seen in English GUM clinics 1949-93 Figure 8. New cases of Chlamydia seen in English GUM clinics 1949-93 At the same time as new cases of Gonorrhoea reaching its highest ever value TFR reached an all time low of 1.66 in 1977.

After 1977 we see a slight increase to 1.87 in 1980 and then plateaus off over the next 13 years. It could be suggested that the lowest ever fertility rates in England and Wales has a direct relationship with the highest number of new cases of Gonorrhoea and the relatively more consistent TFR of 1.8 between 1980 and 1993 coincides with the decline in the number of new cases of Gonorrhoea and Chlamydia reported by GUM clinics.

To reinforce the aims of the study the null hypothesis Ho predicts no relationship between decreasing fertility rates in England & Wales and the increase in number of STI's seen by GUM clinics. In order to accept or reject the null hypothesis, total cases of STI's & TFR's were entered into SPSS and correlated. As all the data met parametric tests and is of an interval level of measurement a 2-tailed Pearson's correlation was used. The data set for new cases of STI's are incomplete so only 1993-68, 1959, & 1949 figures were correlated with TFR. The 1949 value for cases of STI's seen in GUM clinics were assumed as the 1951 value as very little increase is seen between 1949 and 1959.

SPSS Pearson's correlation data. Pearson's correlation coefficient (r) gives a value of 0.732. With n=26, Pearson product moment correction values give a significance (p) at the 0.01 level, which confirms that given by SPSS. Therefore the null hypothesis is rejected and it can be suggested that decreasing fertility rates can be associated with increasing cases of STI's. Increased sexual risk behaviour accounts for much of the rise in STI diagnosis however delays of up to a week for urgent and as much as four weeks for non urgent appointments increases duration of infectiousness which in turn increases STI incidence. Other reasons for the increases in cases of STI's include increased acceptability of GUM services, increased awareness both professionally and public, and improved diagnostic testing (PHLS et al 2002).

It is also important to consider that cases of STI's in the population is underestimated as diagnoses made in non GUM clinics go un-reported in this type of data set and infections such as gonorrhoea & genital chlamydial infection are often asymptomatic and subsequently go un-diagnosed (PHLS et al 2002) Regardless of the fact that STI's are underestimated they still only occur in a small fraction of the population and therefore it is important to consider other factors that lead to decreasing total fertility rates in England & Wales.

More recently the most dramatic change in fertility rates in England and Wales has been a shift towards later childbearing (Ruddock et al 1998). Figure 4 shows that since 1980 fertility rates in the age group of 30-34 & 35-39 have been increasing from 0.353 & 0.112 respectively in 1980 to 0.450 & 0.199 respectively in 1998. This coincides with decreasing fertility rates between the ages of 20-24 & 25-29. Fertility rates of this age group were 0.564 & 0.668 respectively in 1980, and 0.378 & 0.561 respectively in 1998. In terms of fertility rates the result of later childbearing meant that the TFR of these two age groups (20-24 & 25-29) & (30-34 & 35-39) equalled 1.7 and 1.6 in 1980 and 1998 respectively.

This agrees with Hines statement that in the last two decades women have been postponing parenthood in place of entering higher education and paid employment (Hine 2003). Widespread adoption of contraception is seen as the principal cause of fertility decline (Black 1999). The contraceptive pill was introduced to the UK in the early 1960's and by 2002/03 was used by 26% of women aged between 16 and 49, remaining the most common method of contraception used (www.statistics.gov.uk). One obvious result that highlights the importance of the contraceptive pill to fertility rates was the pill scare of 1977. The Royal College of General Practitioner's and University of Oxford/FPA published studies which concluded that use of oral contraception increased the risk of death from cardiovascular disease and as a result sales plummeted. In 1978 fertility rates began to rise and continued to do so until 1980 from 1.66 to 1.87 respectively (Bone 1982).

Therefore it can be suggested that the contraceptive pill and the postponement of parenthood has had a much bigger effect on fertility rates than that of STI's. In fact one article suggests that women who do use contraception are usually more sexually active and have more sexual partners thus are at a higher risk of STI's (Chandran 1993). Therefore the contraceptive pill can be seen as a double edged sword in that it has the affect of decreasing fertility rates whilst at the same time increasing cases of STI's.

In conclusion, the case study revealed that fertility rates in England & Wales have been declining since 1964 and as a result have been lower than the necessary level for replacement of generations since 1974. The study found that there is a significant relationship between the number of new cases of STI's, p = 0.01, and TFR's. This can be explained for example by the increase of cases of Gonorrhoea and Chlamydia which if untreated lead to pelvic inflammatory disease and tubal factor infertility. However the importance of STI's in the decline of fertility in England & Wales is somewhat insignificant compared to that of the contraceptive pill or the recent trend of parenthood postponement.