Declining fertility rates are one of the factors driving a decline in U.S. population growth, according to a Population Reference Bureau (PRB) analysis of U.S. Census Bureau data. Lower immigration levels and population aging are additional factors in declining population growth.
According to the analysis, from 2010 to 2011, the U.S. population grew 0.7 percent after averaging 0.9 percent each year from 2000 to 2010.
"There's two parts of this," says Mark Mather, PRB associate vice president for Domestic Programs. "There's the declining fertility rate, which is the number of births per woman, and there's the declining total number of births, which is a different issue and sometimes caused by other factors, including trends in immigration. If there's fewer people living in the United States who are of reproductive age, then that can also contribute to a decline in the number of births just because there's fewer potential parents."
If you have had children, with or without fertility treatment, and are having difficulty getting and/or staying pregnant again, you may have secondary infertility. It’s not uncommon. In fact, Dr. John Norian says that more than 50 percent of the patients he sees have secondary infertility.
A recent study revealed a “dramatic shift in the number of chromosomal errors in blastocysts from women 40 and older, as a result of severe chromosome instability.”
“When eggs get older the machinery to split the chromosomes gets more and more unstable and more and more errors occur even in the same embryo,” says Dr. William Schoolcraft, Founder and Medical Director of Colorado Center for Reproductive Medicine (CCRM). CCRM researchers analyzed 9,030 blastocysts (day 5 embryos) that were determined to be aneuploid following comprehensive chromosomal screening (CCS). The study showed that as women age fewer chromosomes have one error, and the likelihood increases of having chaotic blastocysts -- those with three or more errors.
Women 30-34 have a 63 percent chance of getting pregnant in a one-year period and a 20 percent chance of miscarriage. This is because there are somewhat fewer eggs and more of these eggs are poor quality. After 35 the decline in fertility become more significant and the miscarriage rate rises as well. Women 35 to 39 have a 52 percent chance of getting pregnant in a one-year period and a 25 percent chance of miscarriage.
Over 40 and trying to conceive? The reality is, it is rare that women in their 40s naturally conceive—women 40-45 have about a five percent chance of getting pregnant naturally each month. Miscarriage rates are high: a 40-year-old has a 33 percent chance of miscarriage and women over 45 have a miscarriage rate as high as 50 percent or more.
In recent years, more and more women are waiting until their 30s and 40s to start a family. In the U.S., about 20 percent of women have their first child after age 35. Unfortunately, infertility increases with age ― about one third of women over 35 have fertility problems.
It is widely known that as a woman’s age increases, her fertility declines, and as a result many couples are hesitant about embarking on the in vitro fertilization process. The journey can be challenging, expensive, and fraught with emotion. But as our technology has improved over the last several years, the impact of the mother’s age has become much less of an issue, though it certainly remains an important consideration.