Legs crossed at the gender scan: does it mean a girl?

Do crossed legs at the scan mean a girl?

A scan reads the baby’s anatomy, so what it shows is the baby’s sex, if the sonographer can see it. Crossed or closed legs don’t change what’s there. They hide it.

What the sonographer needs to see depends on the week. In the late first and early second trimester, the call rests mainly on which way a small bud between the legs, the genital tubercle, points. By the late second trimester, it rests on a direct look at the genitals, a 2009 review explains (Odeh and colleagues, 2009). Nub theory, explained covers the early method. Either way, the area between the legs has to be in view.

When it isn’t, “can’t tell” is the careful answer. In England, the NHS says a sonographer can’t be 100% certain of the sex: “if your baby is lying in an awkward position, it may be difficult or impossible to tell” (NHS). A private clinic in Addis Ababa, Ethiopia, scanned 435 women from 16 weeks to term and reached 269 of the mothers, with 275 babies, by phone after delivery. When the area between the legs wasn’t well seen, the team recorded the sex as not determined (Gelaw and Bisrat, 2011).

We found no study linking a baby’s leg position to its sex. In October 2026, we searched the web and the Directory of Open Access Journals for one. The leg-position studies we found were about breech babies and birth, not about boy or girl.

Where the idea comes from

We couldn’t trace the crossed-legs tale to a source. The closest thing we found is an old scanning shortcut. “Absence of scrotum or penis was previously taken as a girl,” the Ethiopian team noted, adding that recent studies warn against it.

Their own results show why. The team called a baby “probably female” when the area between the legs could be seen and looked empty. Of those 30 babies, 17 turned out to be girls. “This shows empty perineum doesn’t mean simply female,” the authors wrote; the perineum is the area between the legs. Can an ultrasound be wrong about the gender? covers the other ways a hidden view leads to a wrong call.

The tale also gets lucky. In the U.S., 1,046 to 1,059 boys were born for every 1,000 girls each year from 1940 to 2002 (CDC). So any “girl” guess comes true a little under half the time. That’s also why the Chinese gender chart can seem to work. Our boy or girl quiz puts other old wives’ tales to the test, just for fun.

Why babies cross their legs

Babies move, rest and settle into positions, and a scan catches whichever one your baby is in.

Position may shape the legs, too. Researchers at VU University Medical Centre in Amsterdam scanned 10 breech babies and 10 head-down babies every week from 33 weeks until birth, watching their legs for 15 minutes each time. The head-down babies crossed their legs significantly more. The breech babies showed “a clear preference” for straight legs (Fong and colleagues, 2009). The baby’s position in the uterus “does influence” its posture and motor development, the authors concluded. They didn’t compare boys with girls, and 20 babies late in pregnancy can’t speak for a scan at 14 weeks.

Do boys and girls move differently?

Studies disagree, and none we found looked at crossed legs. A team at Washington University in St. Louis counted leg movements on ultrasound videos at 30, 34 and 37 weeks, then after birth. Boys made more leg movements per minute than girls, both before and after birth. The abstract doesn’t say how many babies took part (Almli and colleagues, 2001).

In Japan, a Kagawa University team scored the behavior of 59 boys and 53 girls, all first babies, on 4D scans at 28 to 39 weeks. It found no significant difference in the total score, or in any of its eight parts (Hata and colleagues, 2016). Both teams studied babies from 28 weeks on, not at 13 to 20 weeks. And an average for a group can’t sort one baby, as the heart-rate myth shows.

What a sonographer does when the view is hidden

Hospital guidance, leaflets and studies describe a few moves, all at medical scans, where the sex is extra: in England, finding out “is not offered as part of the national screening programme” (NHS).

1. Keeps looking. In England, the 20-week scan “can sometimes take longer if your baby is moving around a lot or is not in the right position to get clear pictures” (NHS).
2. Tries other views. An ultrasound practice in Victoria, Australia, studied 843 babies scanned at 14 to 20 weeks, when their mothers had amniocentesis for genetic reasons. To cut errors, the authors suggested adding cross-section or tangential views of the area between the legs to the side view (Meagher and Davison, 1996).
3. Asks you to move. If the baby isn’t in an easy position, one NHS trust’s 20-week leaflet says you “may be asked to wriggle your hips, jump up and down or walk around outside” (University Hospitals Sussex). The NHS mentions going for a walk or eating something, then coming back after a short break.
4. Suggests a sweet drink. At the anatomy scan, Cleveland Clinic says, if the baby’s position makes measuring hard, “the technician might ask you to move around a little or take a drink of something sweet” (Cleveland Clinic).
5. Books another day. Sometimes, if the baby “stays in the same position despite trying these things,” the Sussex trust asks you back on a different day, usually within two weeks. The NHS offers another appointment before 23 weeks if clear pictures are still hard to get. These return visits are for the medical checks, not the sex.
6. Says so. “Not sure” is an answer too. A guess from a hidden view isn’t.

Do cold drinks, sugar or a walk get a baby moving?

Some of these tips come from clinics. In a 2013 study at a Sydney hospital, 156 women at 28 weeks or more described their babies’ movements. Some said coffee, sugary drinks or cold water stirred their babies (Raynes-Greenow and colleagues, 2013). That records what women noticed, not whether the tricks work.

Sugary drinks

The evidence is mixed. One small study, by researchers in Israel and Costa Rica, involved 30 healthy women at 14 to 16 weeks. Each was scanned internally for 20 minutes while fasting, then again after taking 110 grams of glucose by mouth. Their babies moved significantly more afterward (Goldstein and colleagues, 2003). The authors concluded that this allows “better ultrasonographic viewing,” but the abstract describes no placebo or comparison group, and it reports only movements, not whether the sex was easier to see. That dose is more than three times the NHS’s daily maximum of 30 grams of free sugars for adults (NHS).

Later in pregnancy, trials haven’t shown that glucose helps. MedlinePlus says a baby “may also wake up” after a snack or sugary drink during heart-rate monitoring, a test usually done in the third trimester. In a non-reactive test, the baby’s heartbeat “didn’t increase when moving or the baby wasn’t moving much” (MedlinePlus). But a 2012 Cochrane review of two trials, with 708 participants, found that glucose “did not decrease the incidence of non-reactive” heart-rate tests, though its abstract doesn’t give the weeks of pregnancy (Tan and Sabapathy, 2012). In a blinded trial at a Tel Aviv hospital, 50 women at 28 to 41 weeks who felt fewer movements were randomly given a glucose drip or a salt-water one. The number of movements the women perceived over the next 30 minutes didn’t differ, and the abstract doesn’t say how many of the 50 were analyzed (Michaan and colleagues, 2016).

If you have diabetes, including gestational diabetes, follow your doctor or midwife’s advice. For gestational diabetes, the NHS says to “avoid sugary drinks” (NHS).

Cold drinks, moving about and your bladder

We found no study that tested cold drinks on their own, or whether walking, wriggling, changing position or a full or empty bladder helps a sonographer see the sex. Bladder instructions are about the picture: a full bladder “makes the ultrasound image clearer” at England’s 12-week scan, the NHS says (NHS). The Sussex trust asks for a full bladder for scans up to 16 weeks, and an empty one after that (University Hospitals Sussex). Follow the instructions you’re given.

Coffee and energy drinks

We found no study of whether caffeine helps a sonographer see the sex. If you have caffeine, it counts toward a daily limit: the NHS says to have no more than 200 mg a day, because too much “has been linked to a higher chance of miscarriage and stillbirth.” A cup of instant coffee has about 100 mg, a can of cola about 40 mg, and a 250 ml can of energy drink about 80 mg (NHS). A 2010 ACOG committee opinion says moderate caffeine, less than 200 mg a day, “does not appear to be a major contributing factor in miscarriage or preterm birth.” Its link to growth restriction “remains undetermined,” the opinion adds (ACOG Committee Opinion 462).

Why “come back” beats a guess

A second look costs you time. A call based on seeing nothing isn’t much better than a coin toss, as the Ethiopian “probably female” calls above show. Waiting helps in another way, too: calls get surer as the weeks pass.

If your sonographer couldn’t see, ask what got in the way and when another look would help. “90% sure it’s a girl”: what a sonographer’s confidence means explains how to read a hedged call and plan around it.

The medical anatomy scan is one more chance. In the U.S., it’s at about 18 to 22 weeks, and whether the technician can see the genitals depends on the baby’s position, Cleveland Clinic says (Cleveland Clinic). In England, the 20-week scan is usually at 18 to 21 weeks (NHS), and finding out “depends on the policy of your hospital” (NHS). When can you find out your baby’s gender? sets out every route, from blood tests to birth.

Worried about movements? Call your doctor or midwife

A keepsake scan, ours included, doesn’t check on your baby’s health. If you’re worried about your baby’s movements, call your doctor or midwife now.

Early on, you may not feel anything yet. The NHS says you should start to feel your baby move between 16 and 24 weeks, and perhaps not until after 20 weeks with a first baby. If you haven’t felt movement by 24 weeks, it says to tell your midwife (NHS).

Once you can feel your baby move, a change matters. The NHS says to call your midwife or maternity unit immediately if your baby is moving less than usual, you can’t feel movement anymore, or the usual pattern changes. “Do not wait until the next day – call immediately, even if it’s the middle of the night.” A home Doppler is no substitute: “Even if you hear a heartbeat, this does not mean your baby is well,” the NHS says.

Call rather than trying to get the baby moving first. One NHS trust in England was asked whether a cold drink or something sweet would wake a baby. Its answer: “No, your baby should be moving on their own without any external stimulation” (North Tees and Hartlepool NHS Foundation Trust). In a 2020 article for doctors, Heather Florescue, MD, wrote that the advice for decreased movement should be to come in and be checked. Ice water, orange juice or a sugary meal shouldn’t be suggested, she wrote, “because it is not supported by the literature” (MDedge).

A shy baby at our studio in Glendale

If your baby is being shy, we take longer. Once we have a clear view it can be over in 2 minutes. A Gender Confirmation at our studio in Glendale, Los Angeles County, is a 2D scan, “the classic black-and-white picture.”

No ultrasound can promise 100%. When we can’t be sure, we say so, and you come back for a free re-check. In the words of our promise: “If we can’t tell with confidence, we don’t guess. You come back, and the second look costs nothing.” We book from 13 weeks, and we’re surest from 15. If you can wait until 15, do: we’re more confident, and a second look is less likely.

It’s a keepsake, not a medical exam: it doesn’t check your baby’s health or anatomy, and it doesn’t replace the anatomy scan or any appointment with your doctor or midwife. The FDA and the AIUM discourage scans done only for keepsakes (FDA, AIUM); Safety, in plain words quotes both. Ready to book? Finding out with us explains the session, and our prices page lists what it costs.

Still counting the weeks? Enter your due date, and the planner shows which of our sessions you can book now and which open next. The date you type stays on your device.

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