"In the United States, a woman who lives to be 90 years old has a 1 in 8 risk of being diagnosed with breast cancer.  With 203,500 cases expected, breast cancer will be the most frequently diagnosed nonskin malignancy in U.S. women in 2002. In the same year, breast cancer will kill approximately 39,600 women, second only to lung cancer as a cause of cancer mortality in women."

(Source: "Breast Cancer (PDQ(r)): Prevention," National Cancer Institute, National Institutes of Health, http://www.cancer.gov/cancer_information/doc_pdq.aspx?viewid=D972A74B-D25A-4F86-B8ED-33EB3C0450E4&version=1#1.21.)

"At the Fred Hutchinson Cancer Research Institute in Seattle, veteran cancer researcher Janet Daling and a team of scholars found that, in her words from this 1994 study, '[a]mong women who had been pregnant at least once, the breast cancer rate in those who had experienced an induced abortion was 50 percent higher than among other women.  Highest risks were observed when the abortion was done at ages younger than 18 years...or at least 30 years of age or older.'"

(Source: Tom Hoopes, "When Abortion Kills Twice: The Breast-Cancer Link," Crisis, vol. 30, no. 8 [September 2002], p. 20.)

As more and more American women have opted to postpone motherhood, pediatricians have found themselves spending more and more time in the hospital neonatal unit trying to save dangerously undersize infants.  The linkage between delayed childbearing and low-birth-weight (LBW) babies recently received attention in an article published in Pediatrics by a team of epidemiologists from the University of Calgary.   Analyzing data for all live and stillborn infants for the province of Alberta between 1990 and 1996, these Calgary scholars uncover evidence strongly implicating delayed maternity as a prime cause of "the recent increase in LBW and preterm delivery." 

The data collected by the Canadian researchers reveal that "delayed childbearing had a substantial impact on the increased incidence of LBW and preterm birth in most weight and gestational age subgroups."  The researchers calculate that, compared to younger mothers, "those aged 35 and older are at a 20% to 40% increased risk of LBW and preterm delivery."  This increased risk translates into more dead and sickly babies, since "Low birth weight (LBW) and preterm delivery are the most important determinants of neonatal mortality, as well as infant and childhood morbidity," with "LBW contribut[ing] 65% to 75% of neonatal deaths" and low-birth weight and preterm infants frequently suffering from "health problems after health discharge and [therefore requiring] higher rates of rehospitalizations than full-term peers." 

And unfortunately, the fraction of children born to older mothers has been rising on both sides of the border.  The Calgary scholars point out that the rising percentage of first births among babies born to Canadian women ages 35 and older reflects a parallel trend documented among American women: "Between 1970 and 1990," they report, "the proportion of first births in the United States increased >100% among women aged 30 to 39 years, and 50% among women aged 40 to 44 years." 

Why are so many women postponing motherhood?  The authors of the new study list a number of reasons for delayed childbearing, most of them reflecting cultural changes: "pursuit of advanced education, the expanded role of women in the workplace, contraceptive advances, infertility, delayed and second marriages, and financial issues such as the preference for dual-income families."

But whatever its causes, delayed childbearing does not augur well for healthy infants.  The authors of the new study predict that "the number of infants who require neonatal transport, intensive care, and ongoing medical care will continue to rise if the trend toward delayed childbearing continues."

(Source: Suzanne C. Tough et al., "Delayed Childbearing and Its Impact on Population Rate Changes in Lower Birth Weight, Multiple Birth, and Preterm Delivery," Pediatrics 109 [2002]: 399-403.)