At 14 weeks pregnant, your fetus is roughly the size of a lemon. Crown-to-rump length (measured from the top of the head to the bottom of the torso, since the legs are curled up) is about 8.1 to 8.5 centimeters, or just over 3 inches. Weight at this stage is roughly 40 to 45 grams, a little over an ounce.
What Those Measurements Mean
Crown-to-rump length is the standard measurement used in early pregnancy because the legs are tucked tightly against the body, making a full head-to-toe measurement unreliable. By 14 weeks, your fetus has grown considerably from the tiny cluster of cells at conception, but it still fits comfortably in the palm of your hand. If you’ve had an ultrasound around this time, the technician likely measured this crown-to-rump length to confirm gestational age and check that growth is on track.
There’s a normal range for size at any given week. The National Institute of Child Health and Human Development maintains fetal growth charts with percentiles, similar to the growth charts pediatricians use for babies after birth. A fetus measuring anywhere between the 3rd and 97th percentile is generally considered within the normal range. Small variations in size at 14 weeks are common and don’t automatically signal a problem.
What’s Developing at 14 Weeks
Size is only part of the picture. At 14 weeks, a lot is happening beneath the surface. The kidneys have started producing urine, which contributes to the amniotic fluid surrounding the fetus. The liver is developing, and the pancreas has begun making insulin, the hormone that will eventually regulate blood sugar. Eyelids have formed but remain sealed shut, and fingernails are taking shape.
External genitalia are also forming during this stretch. While they’re not yet fully differentiated, the basic structures are becoming visible on ultrasound. The fetus is increasingly active, too, making small movements like flexing and stretching, though you likely won’t feel any of that for several more weeks.
Can You Find Out the Sex at 14 Weeks?
Many parents are curious whether a 14-week ultrasound can reveal the baby’s sex. The short answer: it’s possible but not guaranteed. Accuracy of ultrasound-based sex determination improves steadily through the early second trimester. At 14 weeks, studies put the accuracy rate at roughly 90%, up from about 75% at 12 weeks and just 46% at 11 weeks.
Several things can make it harder for the technician to get a clear answer. If the fetus is in a curled-up position, if the umbilical cord happens to be between the legs, or if the baby is especially active during the scan, it may be difficult to see the genitalia clearly. For these reasons, many providers prefer to wait until the anatomy scan around 18 to 20 weeks, when accuracy is higher and the view is much clearer. If you’ve had a blood-based prenatal screening test (like NIPT), that can identify fetal sex with very high accuracy as early as 10 weeks, regardless of the baby’s position.
Skin, Hair, and Body Changes Ahead
At 14 weeks, the fetus’s skin is still translucent and paper-thin. Over the next couple of weeks, a fine layer of hair called lanugo will begin to grow, typically appearing between 16 and 20 weeks. This soft, downy hair serves a surprisingly important purpose: it helps a waxy coating called vernix stick to the skin. Vernix acts as a waterproof barrier, protecting the fetus’s delicate skin from the amniotic fluid it’s floating in. Without that protection, the fluid could irritate or damage the skin over months of constant exposure.
Lanugo also helps regulate the fetus’s body temperature before enough body fat accumulates to do that job, and the tiny hairs send vibrations to sensory receptors in the skin that actually stimulate growth. Most babies shed their lanugo before birth, though premature babies are sometimes born with patches of it still visible.
How Growth Progresses From Here
The 14-week mark sits right at the start of the second trimester, and growth is about to accelerate. Over the next few weeks, the fetus will roughly double in length and gain weight more quickly. By 20 weeks, crown-to-rump length reaches about 16 centimeters (over 6 inches), and weight climbs to around 300 grams (about 10 ounces). The proportions shift noticeably, too. At 14 weeks, the head makes up about half the total body length. By the middle of the second trimester, the body catches up and the proportions start to look more like those of a newborn.
If your provider has noted that your fetus is measuring slightly larger or smaller than average at 14 weeks, a single measurement rarely tells the whole story. What matters more is the growth trend over time, which is why you’ll have additional measurements at future appointments. Consistent growth along a given percentile curve, even a lower one, is typically more reassuring than any single snapshot.