The developing baby is now called a fetus. The eyelids begin to fuse to protect the eyes. The fetus begins doing occasional breathing movements, although it gets oxygen through the umbilical cord. The skin becomes less translucent, and genitals begin to form. Length: almost 1 ¼ inches.
Congratulations, your uterus has swollen to the size of a softball! Looking in the mirror, your shape has definitely changed: less waist and more chest.
Breasts are busiest in the first trimester. During the first few weeks, progesterone causes milk glands to develop and estrogen stimulates growth of the milk ducts. Breasts typically expand one or two bra cup sizes, veins get darker, and nipples get larger, more erect and darker so that eventually, the baby can find them easily.
Your weight gain may be picking up—though don't worry if you haven't gained any by now. Bottom line, if your provider isn't concerned about how much or how little you've gained, you shouldn't be either.
WHO IT’S OFFERED TO: All women.
WHEN IT’S OFFERED: At 10 to 13 weeks.
WHAT IT SCREENS FOR: Chromosomal defects such as Down syndrome and trisomy 18 (an often lethal defect); some cardiac defects.
HOW IT WORKS: Blood is drawn from the mother, and three fetal proteins are measured. These results are combined with the results of a detailed ultrasound (nuchal translucency) that measures the thickness at the back of the fetus’s neck.
HOW EFFECTIVE IT IS: It has an 80 percent to 85 percent detection rate for Down syndrome, with a 4 percent to 6 percent false-positive rate.
WHAT IF …? If you have a positive screen and are not comfortable with the odds, you may opt for a diagnostic test to determine if your baby has a defect. Another option is to do an additional screen in the second trimester—but this will not give you a definitive answer, either.
Things to think about this week
For some women, swollen and very tender breasts are the first clues they’re pregnant: Right from the start, they’re preparing for their job of producing milk. Here, Heather Weldon, M.D., an OB-GYN in Vancouver, Wash., answers some of the most common questions about your mammaries during pregnancy. How your breasts will change during pregnancy.
NEW: Get the TRIMESTER GUIDE FREE On Your iPad or iPhone!
When you download the Fit Pregnancy Magazine app from iTunes you receive our special enhanced and advice-packed Trimester Guide free. Get it now.