Can assisted reproductive technologies help to offset population ageing? An assessment of the demographic and economic impact of ART in Denmark and UK.

Governments worldwide are searching for ways to cope with ageing populations as the demographic shift towards fewer and later births takes hold. The potential contribution of assisted reproductive technologies (ART) to increasing fertility rates has not yet been explored. This paper describes a preliminary study into the impact ART policies might have on population ageing. A deterministic model is developed to quantify the effects of ART policies on total fertility rate (TFR), and tested using data from the UK and Denmark. The population structure for 2050 is modelled to translate fertility rates into time-dependent population dynamics, and the costs of potential ART policies are investigated. If access to ART in the UK were increased to the level of Denmark, the TFR would increase by 0.04, from 1.64 to 1.68. The cumulative effect on the population structure would be a 1.7% decrease in old-age dependency ratio in 2050. Although the empirical models do not include behavioural components, the results demonstrate that ART does have potential to contribute to TFR and influence population structure, and that the direct costs associated with adopting ART as a population policy are comparable with those of existing policies commonly used by governments to influence fertility.

Does inbreeding lead to decreased human fertility?

In most Western countries there is a widespread belief, fostered in part by historical prejudice and religious proscription, that inbreeding in human populations causes a reduction in fertility. Support for this belief has been claimed in HLA-based studies, with increased rates of fetal losses suggested in HLA-compatible unions. To critically assess the overall status of fertility in consanguineous unions, data on 30 populations resident in six countries were collated from a systematic review of the literature. The mean numbers of live births were then compared in four consanguinity test categories, ranging from second cousin to uncle-niece/double first cousin, and corresponding non-consanguineous reference groups. Linear regressions indicated a positive association between consanguinity and fertility at all levels of inbreeding, attaining statistical significance at first cousin level (p < 0.0001). The results were, however, subject to a number of potential limitations, in particular lack of control for important socio-demographic variables. To overcome this problem, data on first cousin marriages were abstracted from the National Family and Health Survey conducted in India during 1992-1993. Multivariate analysis showed that fertility in first cousin unions was positively influenced by a number of variables, including illiteracy, earlier age at marriage and lower contraceptive uptake, but the most important of these parameters were duration of marriage and reproductive compensation. In net terms, consanguinity was not found to be associated either with a significant positive or negative effect on fertility.

The comparative role of consanguinity in infant and childhood mortality in Pakistan.

As part of the 1990/1991 Pakistan Demographic and Health Survey, data were collected on the outcome of 26,408 births to 6,611 women, with mortality rates investigated at specific age intervals during the first 5 years of life. Bivariate and multivariate logistic regression analyses were employed to examine the comparative roles of consanguineous marriage and a number of demographic and socioeconomic factors, including the sex of the child, maternal age, maternal education, birth interval and birth order, as determinants of early death. The results indicate that, even after controlling for these non-genetic variables, inbreeding at the level of first cousin exerted a significant adverse effect on survival in four of the five age intervals examined, neonatal, post-neonatal, infant and under 5 years.

Consanguineous marriage within social/occupational class boundaries in Pakistan.

Data on patterns of consanguineous marriage were collected from 5340 families resident in eight cities in the Pakistan province of Punjab. To assess whether social and/or occupational class was interacting with consanguinity, information also was obtained on the hereditary qaum to which each family belonged. In the present generation 46.5% of all marriages were contracted at the level of second cousin or closer, with an average coefficient of inbreeding (F) of 0.0286, and the results indicated that in each of the seventeen qaums there was strong preference for marriage to a close biological relative. However, significant differences existed in the distribution of consanguineous marriage by qaum membership, which could interfere with the interpretation of studies into the biological effects of inbreeding.

Consanguinity as a determinant of reproductive behaviour and mortality in Pakistan.

To determine the prevalence of consanguineous marriages and estimate the effects of consanguinity on reproductive behaviour and mortality, household and hospital-based surveys were conducted in 11 cities in the Pakistan province of Punjab between 1979 and 1985. The 9520 women interviewed reported 44,474 pregnancies, with data collected on maternal and paternal ages at marriage, abortions/miscarriages, stillbirths and deaths in the first month, at 2-12 months and 2-8/10 years. Six categories of consanguineous marriage were included: double first cousin, first cousin, first cousin once removed/double second cousin, second cousin, bradari (brotherhood) and non-consanguineous. Marriages contracted between spouses related as second cousins or closer accounted for 50.3% of the total, equivalent to an average coefficient of kinship (alpha = sigma piFi) of 0.0280. Unions between close biological relatives were characterized by younger maternal and paternal ages at marriage and reduced spousal age difference, but a longer time to first delivery. Overall, they exhibited greater fertility than non-consanguineous couples. Antenatal and postnatal mortality were assessed by consanguinity and age interval. Consanguinity-associated deaths were consistently higher in the neonatal, infant and childhood periods. The consequences of these outcomes on the health of the present and future generations is assessed.

PIP: There are 20-55% of all unions in Africa and Asia that are marriages between close biological relatives (consanguinity). All major religious groups in Asia, except the Hindus and Sikhs in North India, report consanguineous marriages. In the assessment of the determinants of reproductive behavior and postnatal mortality, retrospective data on 9520 families in 11 cities in Punjab province in Pakistan between 1979 and 1985 were examined. Background variables were age of both partners at age of marriage, spousal age difference, time to first delivery, number of pregnancies, number of abortions/miscarriages, stillbirths, death in the first month, at 2-12 months, and at 2-8/10 years. Consanguinity was defined as marriages between second cousins of closer and included the following: double first cousin, first cousin, first cousin once removed or double second cousin, second cousin, and nonconsanguineous. The results showed that 50.25% of marriages were between second cousins or closer. 37.07% were first cousin marriages, 11.72% were first cousin once removed or second cousin marriages, and .56% were second cousin unions. 33.93% were "bradari" marriages, which denoted fraternal or paternal lines and were classified as nonconsanguineous. Mother's age at first marriage was 18.35 years and father's age at first marriage was 23.28 years for double first cousin unions vs. 19.74 years and 25.97 years, respectively, for nonconsanguineous unions. Spousal age differences were also negatively associated with consanguinity. There were positive associations between mean number of pregnancies and live births and consanguinity. Mortality rose from 16.36% in nonsanguineous pregnancies to 20.09% among second pregnancies, to 22.13% among first cousins, and 38.97% among double first cousins. This findings suggest the expression of harmful recessive genes. Caution is urged in this interpretation because age and socioeconomic status were not controlled. Further data collection and analysis are urgently needed to examine carefully the effects of marriage to a close relative on mortality.

Late follow-up in spina bifida cystica.

The further progress of the survivors in 1969, of a group of 150 babies born with spina bifida cystica in the period 1960-66 is described. Children with a meningocele continued to do well. Those with a myelomeningocele are divided into 2 groups. There were 4 late deaths and a considerable degree of handicap in the group of 23 in whom the spinal cord was exposed on the surface as a plaque at birth. There were 2 late deaths and a much lower incidence of handicap in the group of 25 in whom only ectopic nervous tissue was found in the sac at birth. The incidence and treatment of hydrocephalus is described. Changes in the attitude to the treatment of a neonate with a myelomeningocele are discussed.