23 weeks after fertilization (25 weeks LMP), Baby Chris is 13 and a half inches long and weighs a pound and a half—roughly the size of a rutabega.
|Illustration via BabyCenter.com|
The fetal respiratory rate can rise as high as 44 inhale/exhale cycles per minute at 22 to 26 weeks. This rate changes according to maternal carbon dioxide (CO2) levels, strongly suggesting that the respiratory center in the brainstem of the fetus already detects and responds to changes in CO2 levels in the blood. This respiratory response to CO2 levels is similar to that seen in newborns and adults.For more fetal development facts, download the free "See Baby" app on your smartphone.