Somewhere between finding out you're pregnant and your first appointment, ultrasounds become a given — something that just happens, on a schedule, without much explanation of why. Almost nobody stops to ask: what exactly are we checking for each time, and what do we actually know about what this technology does to a developing baby?

This article is about informed consent, in the fullest sense of that phrase: not just knowing what an ultrasound is for, but knowing what's actually established, what's genuinely uncertain, what your alternatives are, and what your own choices are — so that any decision you make about ultrasounds in your own pregnancy is one you're making with real information, not just going along with a protocol nobody explained.

How Ultrasounds Became Routine

A healthy, full-term pregnancy in the medicalized model typically includes 15–16 provider visits. Ultrasounds have followed a similar trajectory: a 2013 analysis of a low-risk U.S. population found a mean of 4.55 ultrasounds per pregnancy, and more recent industry data (FAIR Health, 2014) put the national average at 5.2 — a 92% increase from 2004. (Sonek, Semin Perinatol, 2013) That's well above the one or two scans that most professional guidelines describe as sufficient for a low-risk, complication-free pregnancy.

Pregnancy apps and mainstream pregnancy content tend to describe this as simply what happens: "by now you've had your second ultrasound," as though it's an assumed, uncontroversial default rather than a series of individual choices, each of which you're entitled to understand and, in most cases, decline. I don't think that framing serves anyone well. Every test, scan, and screening in pregnancy is something you're entitled to ask about: what is this checking for, what happens with the result, and what happens if I decline?

What Ultrasounds Are Actually Used For — and What Alternatives Exist

Ultrasounds serve different purposes at different points in pregnancy — and for several of these purposes, there are other ways to get real information, worth knowing about even if you ultimately choose ultrasound too:

• Confirming the pregnancy is developing in the uterus (first trimester): this is the one purpose where I think the case for an early scan is genuinely strongest. Most ectopic pregnancies do eventually cause pain or bleeding, but about half of women diagnosed with an ectopic pregnancy have no identifiable risk factors beforehand, and a ruptured ectopic pregnancy is a real medical emergency. This is an area where I'd encourage you to make a fully informed choice rather than skip early confirmation based on this article alone.
• Estimating gestational age (first trimester): the due-date and conception-dating articles in this series cover self-tracking alternatives (LMP-adjusted and conception-based calculations) in depth.
• Checking fetal anatomy and development (typically 18–20 weeks): this is the purpose ultrasound is genuinely suited for uniquely — there isn't a non-imaging alternative for visualizing organ and structural development.
• Determining biological sex, if you want to know: this can also be determined through a maternal blood test (non-invasive prenatal testing, or NIPT), typically as early as 9–10 weeks, with high reported accuracy — without any ultrasound exposure at all.
• Checking fetal position and placental location (third trimester): some midwives, and practitioners trained in techniques like belly mapping, can assess fetal position through skilled hands-on palpation. This is a real, legitimate skill worth knowing about — though it's fair to say it doesn't offer the same precision as ultrasound imaging, particularly for placental location, so it's a complement to discuss with your provider rather than a guaranteed substitute in every situation.

The Testing-Culture Toll: Anxiety, Intuition, and Trusting Your Body

There's a cost to constant testing and checking that doesn't show up on any single ultrasound report: the psychological toll of treating your body and your baby as something to be monitored rather than trusted. When every appointment centers on "checking to make sure everything's okay," it can quietly teach you to distrust your own sense of how your pregnancy is going, rather than building confidence in it.

I'm not suggesting you ignore real warning signs — quite the opposite. I think the healthiest posture is trusting that your body and your baby are functioning normally by default, tuning into your own intuitive sense of your pregnancy, and seeking care when something actually feels off, rather than defaulting to proactive, routine surveillance of a process that, for the overwhelming majority of pregnancies, is unfolding exactly as it should.

When Ultrasound Gets It Wrong: False Positives and the "Big Baby" Problem

Here's something worth knowing before you're in the room hearing it: ultrasound-estimated fetal weight is genuinely imprecise, and that imprecision has real consequences.

A study examining this directly found that women who had an ultrasound estimate of fetal weight within a month of delivery had a cesarean rate of 15.7%, compared with 10.2% among those who didn't — and this difference held even though most of those cesareans weren't actually performed for suspected macrosomia. In fact, macrosomia was only listed as the reason in about 9% of the additional cesareans. The risk climbed further when the estimated weight came in above 3,500 grams (about 7.7 lbs). The researchers' conclusion was striking: simply having the estimate — independent of the baby's actual size at birth — appeared to change how labor was managed. (Froehlich et al., AJOG, 2012)

This tracks with something I hear often in this work: a mother is told late in pregnancy that her baby is measuring big, an induction or cesarean gets scheduled to avoid a difficult delivery, and the baby is born a completely normal, unremarkable size — healthy, and very possibly capable of being born vaginally without ever needing the intervention the estimate triggered. Ultrasound weight estimates carry a real margin of error, especially in the third trimester, and it's worth knowing that going in, and asking directly what your provider's plan would be if a "big baby" estimate comes back, before you're in that conversation.

What We Actually Know — and Don't Know — About Safety

Here's where I want to be precise, because this question deserves precision rather than a reassuring soundbite in either direction.

The American Institute of Ultrasound in Medicine (AIUM) — the professional body that sets ultrasound safety guidance used across the medical field — states plainly in its own official position that "there is insufficient justification to warrant conclusion of a causal relationship between diagnostic ultrasound and recognized adverse effects in humans."

Read that sentence carefully: that is not the same as a declaration of safety. It's an acknowledgment that the evidence hasn't established harm — not a claim that harm has been ruled out. The same statement goes on to say directly: "the absence of conclusive studies demonstrating causal relationships does not constitute proof that adverse effects are impossible."

It also notes that some individual studies have reported associations with outcomes like lower birth weight and speech delay, while others have not, and that much of the existing safety evidence predates 1992, when the FDA substantially raised the acoustic output limits allowed in ultrasound equipment — meaning some of what we consider "established safety data" reflects older, lower-powered machines than what's in use today. (AIUM, Prudent Use and Safety of Diagnostic Ultrasound in Pregnancy)

In plain terms: this is genuinely open, unsettled territory, by the ultrasound field's own admission — not a settled "safe" verdict being second-guessed by skeptics, and not a proven-harm verdict being denied by industry either. Anyone telling you it's simple in either direction isn't representing the actual state of the evidence.

The Chinese Research on Fetal Tissue — and Why Some Birth Workers Remain Cautious

Part of why I hold a cautious position on ultrasound goes back to a body of research conducted in China between 1988 and 2011, compiled and translated into English by researcher Jim West in a bibliography documenting over 50 studies, involving more than 2,700 women and over 100 contributing scientists. (Weston A. Price Foundation review of West's bibliography)

Here's how the underlying research was actually conducted: women who had already scheduled an elective abortion volunteered to receive a controlled, measured dose of diagnostic ultrasound beforehand. After the procedure, scientists examined fetal tissue samples — including brain, kidney, eye, and chorioamnion tissue — using laboratory techniques like biochemical analysis, flow cytometry, DNA electrophoresis, and electron microscopy, comparing exposed tissue to unexposed controls. This kind of direct tissue examination is exactly the sort of study that could never ethically be done on an ongoing, wanted pregnancy, which is part of why this body of evidence is so unusual and, to those who take it seriously, so significant.

The bibliography's summary describes cellular and subcellular changes identified in the exposed tissue through these methods, and connects that tissue-level evidence to a broader set of associated later-life conditions. I want to be straightforward with you about where I can and can't independently verify: I can confirm the study design and methodology described above, but I don't have access to the individual underlying papers (published in Chinese-language sources) to independently verify the specific effect sizes behind each associated condition.

This research has not been replicated or reviewed in the indexed, English-language peer-reviewed literature, which is why you won't find it acknowledged in mainstream U.S. obstetric guidance. That doesn't mean it should be dismissed — direct tissue-level evidence is a serious category of evidence, and the ethical impossibility of running equivalent studies on ongoing human pregnancies is exactly why this kind of research is rare and valuable where it exists. It's one of the reasons I don't treat "no proof of harm" (which, as covered above, is genuinely all that mainstream bodies currently claim) as equivalent to "proof of no harm."

I think it's worth knowing this research exists, understanding its actual sourcing and context, and factoring it into your own decision — which is the whole point of informed consent.

The ALARA Principle: Minimizing Exposure Even Within Medical Use

Whatever conclusion you draw from the above, there's a piece of mainstream, uncontested guidance that supports a cautious approach regardless: the ALARA principle — "as low as reasonably achievable" — which is the ultrasound field's own standard for how ultrasound should be used. It calls for keeping exposure time and intensity as low as possible while still getting the needed information, and specifically recommends:

• Avoiding ultrasound for non-medical purposes — elective "keepsake" 3D/4D sessions, sex-reveal videos, and similar uses that aren't diagnostically necessary.
• Limiting Doppler ultrasound (which uses higher energy than standard imaging) in the first trimester, reserved for situations with a genuine medical indication.
• Using the minimum number of scans needed to answer an actual clinical question, rather than scanning on a fixed routine schedule regardless of whether new information is needed.

This is a place where the mainstream guidance and a cautious, minimal-intervention approach genuinely align: even setting the deeper safety question aside, there's no disagreement that unnecessary exposure should be avoided.

Your Right to Informed Consent

Whatever you decide about ultrasounds in your own pregnancy, here's what matters most: you're entitled to ask, for every scan offered to you, what it's checking for, what will be done with the result, what the alternative is, and what happens if you decline. You're entitled to decline non-medically-indicated scans. And you're entitled to a provider who will have that conversation with you without pressure, rather than simply scheduling you for "the next ultrasound" as an assumed default.

If you're in the process of choosing or vetting a care provider, this is exactly the kind of thing worth asking about directly — I've written a full guide to the questions worth asking any medical care provider before you commit to them, which you can find here.

Common Questions

Are ultrasounds proven to be safe?

Not in the sense of "proven" that most people assume. The professional body that sets ultrasound safety standards (AIUM) states there isn't sufficient evidence to conclude a causal relationship between diagnostic ultrasound and harm in humans — but explicitly notes that this absence of proof of harm is not the same as proof of safety.

The 50 Chinese Human Studies of 2,700 women tells us that cellular and subcellular changes were identified in the exposed tissue of aborted babies subjected to ultrasound technology through these methods, and connects that tissue-level evidence to a broader set of associated later-life conditions.

Do I have to get every ultrasound my provider recommends?

No. You're entitled to ask what any recommended scan is checking for and to decline scans that aren't medically necessary for your specific situation, including elective or non-diagnostic ultrasounds.

Are there real alternatives to ultrasound for common questions like baby's position or sex?

For some purposes, yes: biological sex can be determined via a maternal blood test (NIPT), and skilled hands-on assessment (including belly mapping) can often identify fetal position. For others — like detailed anatomy screening — ultrasound remains uniquely suited to the job.

What is the ALARA principle?

"As low as reasonably achievable" — the standard within the ultrasound field itself calling for minimizing exposure time, intensity, and frequency to whatever is actually needed to answer a real clinical question, and avoiding non-medical uses like elective keepsake scans.

Why haven't I heard about the Chinese research on ultrasound and fetal tissue?

It was published in Chinese-language sources and hasn't been independently reviewed or replicated in the English-language, indexed medical literature that most U.S. clinical guidance draws from — which is different from saying it's been examined and rejected. It's part of why some birth workers, myself included, hold a cautious position on ultrasound use.

If you're preparing for birth and want a more complete, holistic foundation — one that covers informed decision-making, your birth team, and preparing as a couple — Download The Wholehearted Family Preparation Guide, free →