New York Times Examines Potential Causes Of Increased Fertility Rate In U.S.A.

The New York Times on Friday examined potential reasons for the increased fertility rate in the U.S., including changes in the real estate market. According to recent data from CDC's National Center for Health Statistics, the total fertility rate -- the number of children a woman will have in her lifetime -- increased to 2.1 children per woman in 2006, the highest number since 1961. The rise reflects increases in birth rates among women in all parts of the country and almost every demographic group except girls under age 15, which was the only decline, the Times reports.

The report found that the fertility rate among Hispanic women in 2006 was the highest with 2.96 children per woman, compared with 2.11 for non-Hispanic black women and 1.86 for non-Hispanic whites. General birth rates were highest in Republican "strongholds" -- Utah had the highest rate followed by Arizona, Idaho and Texas -- the Times reports. Birth rates were lowest in states won by Sen. John Kerry (D-Mass.) in the 2004 presidential election -- Vermont had the lowest followed by New Hampshire, Maine, Rhode Island, New York, New Jersey, Connecticut and Massachusetts -- the Times noted. The report did not include information on religion or socioeconomic status, but researchers have associated religious affiliation and observance with increased fertility rates. A 2007 survey by the Pew Research Center found that 79% of evangelicals said they had children, compared with 73% of nonevangelical Protestants and 62 percent of those who described themselves as secular.

Demographers say it is too early to determine if the increase is a trend or to determine its causes, which might include changes in immigration, the economy and the availability of abortion. Stephanie Ventura, chief of NCHS' reproductive statistics branch, said the increase "could turn around on a dime" but added it was unusual that birth rates in 2006 increased for both teenagers and older women. In the past, a strong economy "contributed to a decline in the teenage birth rate because they saw they could get good jobs, so they put off childbirth," Ventura said, adding, "For older people, a good economy makes them say, 'We can afford to have another child.'"

Robert Engelman -- vice president for programs at the Worldwatch Institute and author of "More: Population, Nature and What Women Want" -- said the availability of housing in the U.S. might be linked to the increased fertility rates. "One reason there are so few children in Italy is that housing is so hard to come by," Engelman said, adding, "Houses are bigger in the U.S. and generally more available. That may help explain why" U.S. residents have more children.

Several population specialists said that housing is one influence on fertility and that it is difficult to ignore other variables, including income or optimism. "If you lower the cost of housing, you're going to lower the cost of raising a child," Seth Sanders, director of University of Maryland's Maryland Population Research Center, said, adding, "But if you look at how much it costs to raise a child, only one-third of the cost is housing. So my guess is that the impact is not very large."

Morris Davis, assistant professor of real estate and urban land economics at the University of Wisconsin-Madison School of Business, said the link between housing and fertility is "something a bunch of us have been thinking about," adding, "If you reduce down-payment constraints, more people can buy homes or buy bigger homes. Does that encourage them to have more kids? I would say nobody knows".

Closer Kinship Linked With Reproductive Success

In a paper published 7 Feb 2008 deCODE scientists establish a substantial and consistent positive correlation between the kinship of couples and the number of children and grandchildren they have. The study, which analyzes more than 200 years of deCODE's comprehensive genalogical data on the population of Iceland, shows that couples related at the level of third cousins have the greatest number of offspring. For example, for women born between 1800 and 1824, those with a mate related at the level of a third cousin had an average of 4.04 children and 9.17 grandchildren, while those related to their mates as eighth cousins or more distantly had 3.34 children and 7.31 grandchildren. For women born in the period 1925-1949 with mates related at the degree of third cousins, the average number of children and grandchildren were 3.27 and 6.64, compared to 2.45 and 4.86 for those with mates who were eighth cousins or more distantly related.

The findings hold for every 25-year interval studied, beginning with those born in the year 1800 up to the present day. Because of the strength and consistency of the association, even between couples with very subtle differences in kinship, the authors conclude that the effect very likely has a biological basis, one which has yet to be elucidated. The paper, 'An association between the kinship and fertility of human couples,' is published online in Science magazine at www.sciencemag.org.

This study provides the most comprehensive answer yet to the longstanding question of how kinship affects fertility in humans. Previous studies in other parts of the world have suggested that the two phenomena are positively correlated, though confounding variables, such as the impact of socioeconomic status on the size of families or age at marriage, have made the results difficult to interpret. The analysis of such a long-term series of data from Iceland effectively eliminates these variables by encompassing an entire population which has historically been highly homogeneous both culturally and economically. Moreover, the results are strikingly consistent from eras in which Iceland was a predominantly poor and rural country, to the present-day era of a highly urbanized society with one of the highest standards of living in the world.

The authors note that the findings are somewhat counterintuitive from an evolutionary perspective because closely-related parents have a higher probability of having offspring homozygous for deleterious recessive mutations, although closer parental kinship can also decrease the likelihood of immunological incompatibility between mother and offspring, for example in rhesus factor blood type. Perhaps most importantly, today's findings also suggest that the recent and dramatic demographic shift experienced in Iceland - from a rural society to a highly urbanized one - may serve to slow population growth, as individuals are exposed to a much broader range of distantly related potential mates. If so, this could be of relevance to slowing population growth in the many other - and much more populous - societies around the world undergoing transition from closely-knit rural societies to more urbanized ones. Indeed, the UN estimates that in the 2007-2008 period the majority of the world's population will, for the first time in human history, live in town and cities.

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'Miracle baby' conceived from 22-year-old sperm

A Canadian couple successfully conceived a baby boy after using sperm that had been stored 22 years, two months and two weeks - a likely record for Canadian fertility treatment. The longest-known storage period for sperm resulting in a live birth is 28 years, according to a 2005 data report in the American journal Fertility and Sterility. Jacek was born in Langley, Canada on 1 November 2007 thanks to Mike Kuzminski's discovery that a Calgary clinic, where he had stored sperm years ago prior to cancer treatment which rendered him infertile, had continued to store his sperm despite no contact or payment from Kuzminski in 22 years.Kuzminski, now a 43-year-old, was diagnosed with Hodgkin's lymphoma at 18. Because chemo and radiotherapy treatment caused 20 per cent of patients to become infertile in the 1980's - a risk that is significantly lower today - his doctor recommended that Kuzminski freeze his sperm. He did and then underwent three years of on-and-off treatment that led to his later-confirmed infertility. When he and his wife Kristin married in 2003, they had accepted that they would not be able to have children. Kuzminski had since forgotten he had frozen sperm before his treatment years ago until his sister reminded him. 'I had assumed that after 15 or 20 years the hospital had gotten rid of my sperm', he said but instead surprisingly found that the clinic had kept it and he owed Rs. 90,000 in storage fees.
Kuzminski seems to have benefited from Canada's current policy indecision regarding gamete storage time-limit guidelines for abandoned frozen sperm. He would not have been so lucky in the UK, where gametes are stored for a maximum of ten years, now with the option to request a five year extension.
Despite great anxiety regarding use of a limited supply of sperm and low success rates of fertility treatments, Jacek was born after undergoing only two intra-uterine insemination (IUI) procedures. They have enough sperm remaining for 19 more attempts but are focusing on their new parenthood and postponing consideration of whether they will try to have another child.