[wideminded]

Among the women studied, those who reported having breast-fed for 13 to 23 months were one-fifth as likely as women who had not breast-fed to develop the arthritis. Those who said they had breast-fed for at least two years reduced their risk by half.

The wording here is not clear. Is there an increase in risk after 23 months or a further decrease?

My wife breastfeeds our son. He seems extremely healthy (knock on wood). Now that he is eight months he has also been eating solid foods for a while. On the subject of breastfeeding in public, my wife was initially very discrete, but she rapidly adopted the attitude that feeding the baby is much more important than worrying about other people's problems with it. Babies digest breast milk more rapidly than formula so they get hungry and need to be fed more often.

[giotto]

I think what they mean is that the first group had one-fifth LESS cancer than the non-breastfeeding group, and that those who nursed for more than two years had half as much as the non-breastfeeders.

[neverdem]

From the Times article:"Among the women studied, those who reported having breast-fed for 13 to 23 months were one-fifth as likely as women who had not breast-fed to develop the arthritis. Those who said they had breast-fed for at least two years reduced their risk by half."

"The wording here is not clear. Is there an increase in risk after 23 months or a further decrease?"

He needs an editor. The 13 - 23 month cohort were one-fifth less likely. The 24 or more month cohort had half the risk of those who breastfed 3 months or less. The following is from the article linked in comment# 35 in medical writing lingo.

RESULTS: Using a multivariate model that adjusted for age, body mass index, smoking, parity, and other hormonal factors, we observed a strong trend for decreasing risk of RA with increasing duration of breast-feeding (P for trend = 0.001). For women who breast-fed (compared with parous women who did not breast-feed), the risk ratios (RRs) and 95% confidence intervals (95% CIs) were as follows: breast-feeding for < or = 3 total months, RR 1.0 (95% confidence interval [95% CI] 0.8-1.2); for 4-11 total months, RR 0.9 (95% CI 0.7-1.1); for 12-23 total months, RR 0.8 (95% CI 0.6-1.0); and for > or = 24 total months, RR 0.5 (95% CI 0.3-0.8).