Sentence:  A statistically significant circadian rhythm for urine volume was revealed in 6 of 10 pregnant women in the first trimester and in 6 of 9 <WSD>puerperas</WSD> on the 7th puerperal day. 
Meaning of the word marked with <WSD> tags:  A woman undergoing puerperium; a woman whose uterus is still enlarged from pregnancy.