One Pound
Your baby weighs about one pound this week. That is a small, specific number that carries an outsized emotional weight. One pound feels both impossibly light and, compared to where you started, extraordinary.
Week 22 is also the week when many women hear the phrase "viability" for the first time in a meaningful way. If you've been reading about pregnancy, you may have come across it already: the point at which a premature baby has a chance of surviving outside the womb with medical support. It is a complicated, context-dependent topic, and it's worth understanding clearly rather than leaving it to internet searches.
Your Baby This Week
Your fetus now measures about 11 inches (27.8 cm) from head to heel and weighs roughly 1 pound (430 grams) [1]. The visual development this week is striking.
- Eyes are structurally complete. All the layers of the eye have formed, though the iris (the colored ring) contains almost no pigment yet. Iris color develops gradually after birth, which is why most newborns have gray or dark blue eyes regardless of what color they'll eventually be [2].
- Inner ear maturity is advancing. The vestibular system, which governs balance and spatial orientation, is now functional. Your baby can detect changes in position and the motion of your body [5].
- Hearing is sharpening. The auditory pathways are continuing to mature, and your baby's responses to sound are becoming more consistent.
- Skin remains thin. The skin is still translucent, wrinkled, and lightly covered in lanugo (fine downy hair). Subcutaneous fat will begin filling in over the coming weeks [2].
- Brain surface is beginning to fold. The characteristic ridges (gyri) and grooves (sulci) on the surface of the brain are just beginning to form. A smooth brain surface at this stage is completely normal [5].
The Viability Threshold: What It Actually Means
Viability is the gestational age at which a premature baby has a realistic chance of surviving outside the womb with intensive medical support. In the United States, 22 to 24 weeks of gestation is generally described as the periviable period, the edge of potential survival [4].
Here is what the medical data shows:
- Before 22 weeks: Survival with any intervention is extremely rare.
- At 22 weeks: Survival is possible with maximal NICU intervention, but outcomes vary significantly by hospital and individual circumstances. Rates are low and complications are common [4].
- At 23 weeks: Survival rates improve meaningfully, and more hospitals will offer active intervention.
- At 24 weeks: Most hospitals consider this the standard threshold for full resuscitation.
Why does this matter at week 22, when you're likely not anywhere near the risk of preterm birth? Because understanding viability in context helps defuse the fear when you encounter the word online or in conversation. The vast majority of pregnancies do not involve preterm birth before 34 weeks. The periviable window is relevant to a small subset of high-risk pregnancies.
If you have risk factors for preterm birth (a prior preterm delivery, cervical insufficiency, a multiple pregnancy), your MomDoc provider will have specific conversations with you about monitoring. For most women at week 22, this is background knowledge, not an immediate concern [3].
Braxton Hicks: Practice Runs
You may be noticing your belly suddenly tighten, hold the tightness for 30 to 60 seconds, and then release. This is a Braxton Hicks contraction, sometimes called a "practice contraction" [3]. A few things to know:
- They are typically irregular and infrequent.
- They are usually painless or mildly uncomfortable, not truly painful.
- They do not cause cervical dilation.
- They can be triggered by dehydration, activity, a full bladder, or no obvious reason at all.
The difference between Braxton Hicks and preterm labor is regularity, intensity, and cervical change. If contractions are coming regularly (every 10 minutes or more frequently), are increasing in intensity, or are accompanied by pelvic pressure or lower back pain, contact your provider promptly [3].
Your Body at Twenty-Two Weeks
- Swelling in the feet and ankles. Increased blood volume and pressure from the uterus on the large veins returning blood from the legs causes fluid to pool by end of day. Elevating your feet, staying hydrated, and limiting prolonged standing helps. Report sudden or severe swelling to your provider, especially if it's accompanied by headache or vision changes.
- Possible Braxton Hicks contractions. As noted above, irregular tightening is normal. Stay hydrated, empty your bladder regularly, and call MomDoc if contractions become regular or painful.
- Back pain increasing. The uterus's growing weight is shifting your lumbar curve forward. Prenatal yoga and attention to posture can reduce the load on your lower back.
The Emotional Side
"I just learned what 'viability' means and now I can't stop thinking about worst-case scenarios." Learning that your baby has reached the threshold of potential survival outside the womb (around 22-24 weeks) should feel reassuring, but for many women it introduces a new category of fear. The word "viability" implies that loss is possible, and that knowledge is hard to un-know. Catastrophic thinking in the second half of pregnancy is common and does not mean you are manifesting bad outcomes. If the intrusive thoughts are interfering with your ability to enjoy the pregnancy or sleep at night, talk to your provider.
What MomDoc Wants You to Know
Your next prenatal appointment is typically around week 24. That visit is one of the more substantive ones: your fundal height will be measured (and should roughly match your gestational age in centimeters), fetal heart tones will be checked, and the glucose screening will be coming up soon.
Your one-pound baby with the newly formed eyes is listening to more than you realize. Their balance system responds to your motion. Their ears are calibrating to your voice. They are already more tuned in to you than the scale number suggests.