The Playbook

10 Weeks Pregnant: From Embryo to Fetus, Plus Screening

By the Guide to Fatherhood editorial team. Last reviewed . 2 min read.

Checked against guidance from organizations like the AAP, CDC, ACOG and NHS (linked below). This is general information, not medical advice. Read our medical disclaimer.

Trimester1
Sizea strawberry
Lengthabout 1.2 in (3.1 cm)

The critical early phase of organ formation is largely complete. From now on, the baby (now called a fetus) mainly grows and matures. Tiny fingernails are starting.

Your to-do list this week

  • Read ACOG's plain-language page on prenatal genetic screening together before the next appointment.
  • Decide together whether you want to learn the baby's sex from screening results, if it's included.
  • Keep the household load where it is. Week 10 is not the week to relax your efforts.
  • Plan a low-key date: a movie at home, takeout she can stomach, early bedtime.
A conversation to have this week

"If a screening result came back high-risk, what would we want to know next?" You don't need answers today, but knowing you can talk about hard things is worth a lot.

The baby this week

At 10 weeks, the end of the embryonic period, your baby is officially a fetus. About the size of a strawberry, the baby has all major organs in place, and from here on the job is growth and maturation (Mayo Clinic). Fingernails are beginning, and the bones are starting to harden (NHS).

How she may be feeling

Still first-trimester tired and queasy for many. Blood volume is rising, which can make her feel warm and short of breath, and her body shape is starting to change. Ask what’s comfortable instead of guessing.

Screening: what dads should understand

From about 10 weeks, couples can choose cell-free DNA screening, a blood test that looks at fragments of DNA from the placenta in her blood. According to ACOG:

  • Screening is optional. Some couples want all the information they can get; others decide not to screen. Both are valid.
  • Screening estimates risk; it doesn’t diagnose. A “high-risk” result means further testing (such as CVS or amniocentesis) is offered to get a definite answer.
  • A low-risk result is reassuring but not a guarantee. Screening doesn’t detect every condition.
  • It may reveal sex chromosomes. Decide in advance whether you want to know.

Your role in the decision

It’s her body and her blood draw, but most couples want to decide together. Read the material, ask questions at the appointment, and say what you think, then respect that she gets the final say on what happens to her body. And if you’re the anxious one, tell her rather than letting it leak out sideways.

Don’t coast

Week 10 is when some dads relax because “it’s been a while.” It hasn’t been that long, and the first trimester is still running. Keep the household load where it is for a few more weeks.

Frequently asked questions

What is cell-free DNA screening?

A blood test from the pregnant person that analyzes small fragments of placental DNA in her blood. It screens for certain chromosomal conditions and can be done from about 10 weeks. It is a screening test: a high-risk result needs a diagnostic test to confirm.

Can cell-free DNA tell the baby's sex?

Often, yes, because it looks at sex chromosomes. Let the lab or provider know whether you want that information or want it kept as a surprise.

Sources

  1. Prenatal Genetic Screening Tests, American College of Obstetricians and Gynecologists
  2. Week 10: Your baby and your body, NHS
  3. Fetal development: The first trimester, Mayo Clinic

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