Your baby, your body, your partner and the prenatal visit, plus tips for the 15th week of pregnancy.

Your baby

By the 15th week of pregnancy, some parents are itching to find out the sex of the baby. Typically, the guess does not happen until the 16th week or so. Waiting a few weeks more may be a good idea as the fetus grows larger and the genital organs are easier to spot. In utero, the fetus may be sucking the thumb or fingers. The sucking reflex is one of the most important instincts a baby has because, without the suck reflex, babies cannot breastfeed or bottle-feed effectively. The fetus now measures between 4 and 4 ½ inches and weighs up to 3 ½ ounces. Hair called lanugo is covering every inch of skin. This hair is fine and silky soft and will continue to grow until the 26th week of pregnancy.

Your body

The uterus continues to grow. This may cause ligaments in the abdomen to stretch causing a bit of pain. Some expectant women, especially those carrying their first pregnancy, could confuse these pains with contractions. If pain exists, let your doctor or midwife know.

At the prenatal visit

At your next appointment, the doctor may pull out a tape measure, ask you to lie down, and begin to measure fundal height about the 15th week. Fundal height is the distance between the top of the uterus and pubic bone. Typically, the fundal height will measure (in centimeters) the same as the week of pregnancy — the 15th week would equal 15 centimeters.

Your partner

Preparing the baby’s room is another tangible way to take part in the new baby’s life. Mom will need help moving furniture, painting, and building the many pieces of baby furniture needed for the room. Assembling other items like strollers, car seats, and changing tables can also help your partner prepare for the new baby.

It can also be helpful to read books on becoming a parent and educating yourself together as one as much as possible before the baby arrives.

Tips for this week

If an ultrasound is scheduled at this time, you may need to talk about the sex issue. Some parents want to know the sex of the baby and others do not. Sex can be determined by ultrasound or amniocentesis. Ultrasound offers a picture of the genital area and a tech can guess, based on experience, the sex of the fetus. Amniocentesis is a bit more reliable as chromosomes are tested to reveal a definitive sex. Decide together if you want to know or not before the exam.