GUIDE
Published on ·Updated on
Your baby is the size of a kumquat — vital organs are functional and bones are starting to harden.
At 10 weeks, development has shifted from building organs to refining them. The brain is producing 250,000 new neurons per minute. Tiny tooth buds are forming beneath the gums. Bones are beginning to harden from soft cartilage into actual bone tissue. The fetus can now swallow amniotic fluid and produce urine. And the NIPT screening window has opened.
Be prepared from day one
“There's a host of reasons why prenatal care is important. The earlier that we can get patients seen, the earlier we can start interventions that can improve these longer-term outcomes.”
Your baby is about the size of a kumquat — roughly 3 centimeters (1.2 inches) from crown to rump and weighing about 4 grams. Small as it is, the fetus is now recognizably human in shape.
The most significant development this week is that vital organs are now functioning in their basic forms. The kidneys are producing urine, which is being excreted into the amniotic fluid. The stomach is producing digestive juices. The liver is making bile. The brain is generating an estimated 250,000 new neurons per minute — a rate it will sustain for the next several weeks as it builds the billions of brain cells needed for a lifetime.
Tiny tooth buds are forming beneath the gums for both the baby teeth and the permanent teeth that will come in years later. Bones are beginning the process of ossification — transitioning from soft cartilage to harder bone tissue. The spine is clearly visible, and the spinal nerves are beginning to stretch out from the spinal cord.
The fingers and toes are now fully separated with no webbing. Nails are beginning to grow. The fetus can bend its arms at the elbows and its legs at the knees. The external ears are nearly fully formed, and the upper lip is complete.
For a look at what happened last week, see our week 9 guide.
You are nearing the end of the hardest stretch of the first trimester. For many people, weeks 10-12 bring the first hints of improvement in nausea and fatigue, though this varies considerably.
Your blood volume has increased by about 25% already and will continue to rise. This increased blood volume is responsible for several symptoms: visible veins (especially on the chest and breasts), occasional dizziness when standing up quickly, and nasal congestion. Your heart is pumping more blood per beat to accommodate the higher volume.
You may notice occasional sharp, brief pains on one or both sides of your lower abdomen. These are round ligament pains — caused by the ligaments that support the uterus stretching as it grows. They are often triggered by sudden movements like standing up quickly, coughing, or rolling over in bed. They are uncomfortable but harmless. You may also start tracking pregnancy weight gain — your provider will monitor the trend over the coming months.
Emotionally, you may feel caught between excitement about the pregnancy progressing and anxiety about waiting for screening results or the end of the first trimester. This in-between period — too early to feel the baby move, too early to look pregnant, still too early for many to share the news — can feel isolating. Lean on your partner, a close friend, or a professional if you need support.
Every pregnancy is different. You may experience all, some, or none of these symptoms.
Screening decisions and symptom management are the focus this week. You are also entering the window when many people start thinking about announcements and logistics.
The NIPT screening window opens at 10 weeks. If you are interested in screening for chromosomal conditions, talk to your provider about the benefits, limitations, and potential results. NIPT is a screening test with very high accuracy, but it is not diagnostic. A positive result does not guarantee the condition is present — it means further testing (amniocentesis or CVS) is recommended to confirm.
Even if nausea is limiting your food choices, try to get adequate calories and fluids. If you have been surviving on a restricted diet due to aversions, a prenatal vitamin is covering many nutritional gaps. As nausea begins to improve in the coming weeks, you can gradually reintroduce a wider variety of foods.
If first-trimester fatigue and nausea kept you sedentary, now is a good time to ease back in. A daily 20-minute walk can improve energy, mood, and digestion. Swimming is excellent during pregnancy — the buoyancy takes pressure off joints and the cool water can feel wonderful.
Many people wait until after the first trimester (around 12-13 weeks) to announce their pregnancy more widely, since miscarriage risk drops significantly after this point. However, there is no rule — some people tell close family early for support, while others wait for specific milestones like a good screening result. Do what feels right for you.
When in doubt, call your provider. No question is too small during pregnancy.
Next week, your baby will be able to open and close its fists, tooth buds will continue developing, and genitals will begin to differentiate. You are three weeks away from the second trimester.
Next up: Week 11. If you are exploring screening options, our NIPT guide explains everything you need to know. The nuchal translucency scan is another key screening tool available over the next few weeks. For ongoing fatigue, see our pregnancy fatigue guide. And for a bird's-eye view of the trimester you are finishing, check out our first trimester guide.
This guide is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider with any questions about your pregnancy.
