Week 19: Hair Sprouts, Ovaries Stockpile, and Round Ligaments Protest

Hair sprouts this week. If your list has been growing for a few months, the popularity curves for each name are worth checking now — a name that surges from rank 800 to rank 80 in two years is a different choice than a name that has been at rank 150 for thirty. So does vernix caseosa, the waxy coat that will protect the baby's skin in amniotic fluid for the next twenty-one weeks. The body is laying down its outer layer. Real hair, on the scalp, the kind that will be there at birth. Up to now the only fetal hair has been lanugo, the fine, peach-fuzz coat that covers the whole body and serves as a temporary insulation layer. This week, the American Pregnancy Association notes that "hair is beginning to sprout on your baby's scalp." Whether your baby will be born bald, mildly fuzzy, or with the kind of dramatic head of hair that gets photographed and put on social media is being settled in this week.

This is also the week of one of the stranger and quieter biological facts in human development. If you are carrying a female fetus, by the end of this week "she already has 6 million eggs formed in her ovaries." That number will fall, sharply, over the next twenty weeks, settling to around one million by birth and a few hundred thousand by puberty. Your daughter will live with the eggs she has by the end of this trimester for the rest of her reproductive life. The most stunning fact about female fertility is that it is built before birth.

This week

Your baby is, per the APA, "still a little under 7 inches (17.8 cm) long" and "weighs about 7 ounces (.2 kg)." The weekly weight gain has accelerated, last week's five and a half ounces have become this week's seven, and that pattern continues for the next six weeks.

Two developmental notes worth pinning down. First, the brain. The APA states that "the parts of the brain that are responsible for the senses are specializing." Up to now, the developing brain has been mostly general-purpose tissue. This week, neurons begin organizing into the specific regions that will handle sight, sound, smell, taste, and touch. The reason newborns can hear their mother's voice within hours of birth is partly that the auditory cortex was being built during weeks like this one. Second, the kidneys. The APA notes that "the kidneys are making urine", the cycle that started around week 12 is now producing meaningful volumes of amniotic fluid every day.

The Cleveland Clinic adds a developmental milestone that the APA omits: hiccupping begins this week. The fetal hiccups some pregnant people start to notice in the second trimester, small, rhythmic, repeating jolts every few seconds — are the diaphragm practicing the motion it will use to breathe at birth. The vocal cords are not yet operating, so the hiccups are silent. Most parents describe the sensation as quietly comic.

The NHS pegs the size at around 17cm and notes that the fetus is now "developing a fine, downy layer of hair called 'lanugo,'" which will mostly shed before birth.

What's happening in your body

The headline symptom of week 19 is round ligament pain. The APA puts it directly: "Round ligament pain represents the primary symptom at this stage, described as 'a sharp pain in the abdomen or hip area on one or both sides as the round ligament stretches.'" The mechanism is mechanical — the round ligaments connect the uterus to the pelvis, and as the uterus enlarges, they stretch. The pain is brief, sharp, often triggered by sudden position changes, and almost always benign.

The other symptom that surfaces around now is dizziness. The APA notes that dizziness "occurs due to low blood pressure and can be managed through positional changes like sleeping on one's side." Lying flat on the back, especially for more than a few minutes, can compress the inferior vena cava and reduce blood return to the heart. Sleeping on the side — preferably the left side, which gives slightly better blood flow through the placenta — is now the recommended default position for the rest of the pregnancy.

The under-discussed symptom of week 19: a sudden, occasionally severe craving for the foods of your childhood. The hormonal weather of the second trimester does specific things to the parts of the brain involved in memory and food preference, and a meaningful number of pregnant people report cravings that map directly back to dishes their parents made. There is no good evidence that the cravings indicate any particular nutritional deficit. They are mostly just one of the small, strange experiences of mid-pregnancy.

The single most useful thing to do this week is reset your sleeping setup if you have not. A pillow between the knees, a pillow under the bump, and a pillow at the back to keep you from rolling onto it in the night. Three pillows total. Most pregnant people resist the setup at first because it looks ridiculous. Most pregnant people accept the setup by week 21 because the sleep is dramatically better.

What your partner can do

Week 19 is a relatively calm week between the anatomy scan and the halfway-point milestone of week 20. Three concrete moves.

Help build the three-pillow setup. Buy the pillows if they are not in the house. Set them up the first night. Sleep around them yourself if necessary — the maternity wedge under the bump does not interfere with the non-pregnant partner's sleep, and your wedging-in beside it tends to reassure the pregnant partner that the new setup is shared, not a banishment.

Learn what fetal hiccups feel like and ask about them. Repeating, rhythmic, every-few-seconds — distinctive enough that you can recognize them across the room when the pregnant partner notices. Asking "are those hiccups?" is a small thing that signals you are paying attention to the same body she is paying attention to.

Start the conversation about the second half of the pregnancy. Specifically: who is taking parental leave and for how long, what the work-life math is going to look like in the third trimester, what nursery or sleep-space decisions need to be made and by when. The first half has been mostly waiting and tracking; the second half includes a lot of practical decisions that compound badly if left to the last weeks.

Names we love this week

Names with small accumulations fit this week — hair sprouting, eggs settling, the brain organizing.

• Esme — French "esteemed, loved" — clean for the small-accumulations week.
• Soren is the Danish form of Severinus. The Kierkegaardian association is the obvious one; the meaning, less obvious, is that it sounds completely different from most American name lists.
• Beatrice means "she who brings happiness" in Latin. A name that has come back from old-fashioned through classic into modern in the last twenty years.
• Zoe — Greek "life". A clean candidate for week 19.
• Saoirse is Irish for "freedom." The pronunciation ("SEER-shah") is the obstacle; the name itself is musical.
• Lincoln means "town by the pool" in English. A presidential association is the obvious story; the underlying meaning is the gentler one.
• Genesis means "beginning" or "origin" in Greek. A name that has surged in the US in the last decade after a long quiet stretch.
• Quinn means "wisdom" or "intelligence" in Irish. One syllable, no waste, a name that has crossed gender lines cleanly.

A piece of advice specifically for week 19: if you are carrying a female fetus, write one sentence in your notes about the six million eggs. Not a paragraph. One sentence. "My daughter has more eggs in her this week than she will ever have again." You will lose the moment in two days if you do not. The fact is one of the small, structurally beautiful facts of human development, and it is the kind of thing your child will ask you about when they are old enough to ask about anything.

Sources

• American Pregnancy Association — Week 19 of Pregnancy
• Cleveland Clinic — Fetal Development: Stages of Growth
• NHS — 21 Weeks Pregnant