When expecting a baby, parents naturally want to understand every aspect of their child's development. Learning about clubfoot pregnancy risk factors helps families prepare and seek early specialist input where needed. Clubfoot — medically known as congenital talipes equinovarus (CTEV) — affects roughly 1 in every 1,000 live births in the United Kingdom, making it one of the more common congenital musculoskeletal conditions. While most cases occur with no identifiable cause, research has uncovered several factors that increase the likelihood.
This article examines what the current medical evidence says about risk factors for clubfoot during pregnancy, which are modifiable, and what screening options exist on the NHS. If you have already received a diagnosis during your 20-week anomaly scan, our separate guide covers next steps in detail.
Understanding How Clubfoot Develops in the Womb
Clubfoot develops during the first trimester when the structures of the foot and lower leg are forming. Between weeks 8 and 12 of gestation, the bones, tendons, muscles, and blood vessels of the foot take shape. In clubfoot, the foot turns inward and downward — the heel points down (equinus), the midfoot twists inward (varus), and the forefoot curves medially (adductus).
The precise mechanism remains incompletely understood, but current thinking points to a combination of genetic predisposition and environmental influences acting during this critical window. What is clear is that clubfoot is not caused by anything the mother did wrong during pregnancy — this is a developmental variation, not a result of negligence.
The Multi-Factorial Model
Researchers classify clubfoot aetiology under a multi-factorial threshold model. This means that no single gene or single environmental factor is responsible. Instead, a combination of small genetic susceptibilities and environmental exposures collectively push development past a threshold where the foot does not rotate into its normal position.
This model explains why the condition can appear seemingly at random in families with no prior history, and also why some families see it recur across generations.
Genetic Risk Factors
Genetics play a significant role in clubfoot susceptibility. While no single "clubfoot gene" has been identified, several genetic pathways are implicated.
Family History
Family history is the strongest known risk factor. The recurrence patterns are well documented:
- If one parent was born with clubfoot, the chance of their child having it is approximately 3-4%
- If one sibling has clubfoot, the risk for a subsequent child is around 2-5%
- If both a parent and a sibling are affected, the risk rises to roughly 10-15%
- For identical twins, when one has clubfoot, the other has a 33% chance
- For non-identical twins, the concordance drops to approximately 3%
These patterns strongly suggest a genetic component but also show that genetics alone do not determine outcomes. Our dedicated article on clubfoot genetics and heredity covers the inheritance patterns in greater depth.
Specific Genes Under Investigation
Genome-wide association studies (GWAS) have identified several candidate genes:
- PITX1 — a transcription factor involved in hindlimb development. Variants near this gene have been linked to clubfoot risk in multiple populations
- TBX4 — another limb development gene associated with lower extremity malformations
- Muscle contractile genes — variations in genes encoding for muscle myosin chains may contribute to the muscle imbalance seen in clubfoot
- Collagen and connective tissue genes — anomalies in connective tissue composition may alter tendon and ligament flexibility during foot formation
These findings are from research settings and are not yet used in clinical screening or prediction. No genetic test for clubfoot risk is currently available on the NHS.
Sex of the Baby
Clubfoot is approximately twice as common in boys as in girls. The male-to-female ratio is roughly 2:1 across all populations studied. The reason is not fully understood but may relate to hormonal influences on muscle and tendon development, or sex-linked genetic factors. For more on this disparity, see our article on why clubfoot is more common in boys.
Environmental and Maternal Risk Factors
While genetics create susceptibility, environmental factors during pregnancy may contribute to whether clubfoot actually develops. These are the factors with the strongest evidence base.
Smoking During Pregnancy
Maternal smoking is the most consistently identified modifiable risk factor for clubfoot. A meta-analysis published in the Journal of Pediatric Orthopaedics found that smoking during pregnancy increases the risk of clubfoot by approximately 30-50%. The risk appears dose-dependent — heavier smoking correlates with higher risk.
The mechanism likely involves nicotine and carbon monoxide affecting blood flow to the developing limb, combined with disruption of gene expression during the critical first-trimester window. Importantly, this is a modifiable risk factor — stopping smoking before or early in pregnancy eliminates this additional risk.
The NHS provides free stop-smoking support for pregnant women through local maternity services, and your midwife can refer you.
Family History of Smoking Combined with Genetics
A significant finding from epidemiological studies is that the combination of maternal smoking and a family history of clubfoot has a multiplicative effect. Women who smoke and have a first-degree relative with clubfoot face a substantially higher risk than either factor alone — estimated at up to 20 times the baseline population risk in some studies.
Oligohydramnios (Low Amniotic Fluid)
Reduced amniotic fluid volume limits the space available for foetal movement. The developing foot needs room to move and rotate through its normal developmental sequence. When fluid is very low — a condition called oligohydramnios — the physical constraint can contribute to positional deformities including clubfoot.
Oligohydramnios has multiple causes including placental insufficiency, premature rupture of membranes, and foetal kidney problems. It is typically identified during routine ultrasound monitoring.
Selective Serotonin Reuptake Inhibitors (SSRIs)
Some studies have found a modest association between first-trimester SSRI use and clubfoot risk. The data are not conclusive, and the absolute risk increase is small. Current NHS guidance does not recommend stopping antidepressants during pregnancy solely because of clubfoot risk — the benefits of treating maternal depression generally outweigh the small potential risk.
If you take SSRIs and are planning a pregnancy, discuss the balance of risks with your GP or psychiatrist. Do not stop medication without medical advice.
Seasonal Variation and Vitamin D
Some epidemiological studies have reported slightly higher rates of clubfoot in babies conceived during winter months, leading to hypotheses about vitamin D deficiency during early pregnancy. Vitamin D is involved in musculoskeletal development, and deficiency is common in the UK, particularly in northern regions.
While the evidence is not strong enough to establish a direct causal link, maintaining adequate vitamin D levels during pregnancy is recommended by NICE for general maternal and foetal health. The NHS recommends all pregnant women take a daily supplement containing 10 micrograms (400 IU) of vitamin D.
Maternal Obesity
Some studies have identified an association between maternal obesity (BMI over 30) and slightly increased clubfoot risk. The relationship is not as strong as with smoking, and the mechanism is unclear. It may relate to metabolic factors, inflammatory markers, or associated conditions like gestational diabetes. Maintaining a healthy weight before and during pregnancy has broad health benefits for both mother and baby.
Amniocentesis
Early amniocentesis (performed before 15 weeks' gestation) has been associated with an increased risk of clubfoot. This is likely due to temporary loss of amniotic fluid creating a constrained environment. Amniocentesis performed after 15 weeks does not carry this same increased risk. Current NHS practice schedules amniocentesis at 15 weeks or later, partly for this reason.
Conditions Associated with Higher Clubfoot Risk
While 80% of clubfoot cases are idiopathic (occurring in isolation), approximately 20% occur alongside other conditions. This is sometimes called syndromic or non-isolated clubfoot.
Neuromuscular Conditions
Conditions affecting nerves or muscles increase clubfoot risk substantially:
- Spina bifida — particularly myelomeningocele, where nerve damage affects foot positioning
- Arthrogryposis — a group of conditions involving joint contractures
- Myotonic dystrophy — an inherited muscular condition
Chromosomal Conditions
Several genetic syndromes include clubfoot as a feature:
- Trisomy 18 (Edwards syndrome)
- Down syndrome (trisomy 21) — less commonly
- Diastrophic dysplasia
- Larsen syndrome
Other Structural Anomalies
Clubfoot can occur alongside other structural birth differences, including congenital hip dysplasia and cleft palate. When clubfoot is detected on ultrasound alongside other anomalies, additional genetic testing may be offered.
Screening and Early Detection on the NHS
The NHS Foetal Anomaly Screening Programme includes assessment of the feet during the 18+0 to 20+6 week anomaly scan. Sonographers are trained to identify foot positioning abnormalities, though detection rates vary.
What the Scan Can and Cannot Tell You
Ultrasound can identify the characteristic position of a clubfoot — the sole of the foot facing upward or inward rather than downward. However:
- Not all cases are detected at the 20-week scan — some mild cases or cases with difficult foetal positioning may be missed
- The scan cannot determine severity — mild and severe cases can look similar on ultrasound
- The scan cannot predict treatment response — the vast majority of clubfoot cases respond well to the Ponseti method regardless of scan appearance
If clubfoot is suspected on the anomaly scan, you should be referred to a specialist Ponseti clinic so you can meet the team before birth. Our article on prenatal clubfoot diagnosis explains this pathway in detail.
What You Can Do: Modifiable Risk Factors
While you cannot change your genetics, family history, or your baby's sex, there are evidence-based steps you can take:
- Stop smoking — the single most impactful modifiable action. NHS stop-smoking services are free and effective
- Take folic acid — while primarily recommended to prevent neural tube defects, adequate folate supports overall foetal development. Take 400mcg daily from before conception through the first 12 weeks
- Take vitamin D — 10mcg daily throughout pregnancy, as recommended by NICE
- Discuss medications with your GP — if you take SSRIs or other regular medications, have a pre-conception discussion about risks and benefits. Never stop medication without medical advice
- Attend all antenatal appointments — regular monitoring ensures conditions like oligohydramnios are detected early
Putting Risk Into Perspective
It is important to understand that even with multiple risk factors, the absolute probability of having a baby with clubfoot remains relatively low. The baseline rate is about 1 in 1,000. Even a doubling or tripling of relative risk still means the vast majority of babies will not be affected.
Equally important: clubfoot is one of the most treatable congenital conditions. The Ponseti method has success rates exceeding 95% when performed by trained practitioners and followed through with proper bracing. A clubfoot diagnosis — whether before or after birth — is not a cause for despair. Children treated with the Ponseti method go on to walk, run, play sport, and lead entirely normal active lives.
Frequently Asked Questions
Q: Can I prevent my baby from having clubfoot?
A: You cannot prevent clubfoot entirely because the largest risk factors — genetics and sex — are not modifiable. However, stopping smoking, maintaining adequate nutrition (including folic acid and vitamin D), and attending regular antenatal care reduce modifiable risks and support healthy foetal development overall.
Q: I had clubfoot as a child. What is the chance my baby will have it?
A: If one parent was treated for clubfoot, the risk of their child having clubfoot is approximately 3-4%, compared to the general population risk of about 0.1%. This means the large majority of babies born to affected parents will not have clubfoot, but the risk is higher than average.
Q: My anomaly scan showed possible clubfoot. Should I be worried?
A: It is natural to feel anxious, but clubfoot detected on the anomaly scan is very treatable. Ask for a referral to a Ponseti specialist clinic before the birth so you can understand the treatment pathway. The prognosis for isolated clubfoot treated with the Ponseti method is excellent.
Q: Does maternal age affect clubfoot risk?
A: Current evidence does not show a strong independent association between maternal age and clubfoot risk. Very young maternal age (under 20) has been linked to slightly increased risk in some studies, but the data are inconsistent.
Q: Is clubfoot caused by the baby's position in the womb?
A: True clubfoot (structural talipes equinovarus) is not caused by the baby's position, though it develops in the womb. Positional talipes — where the foot is temporarily turned due to cramped positioning — is a separate, much milder condition that usually resolves on its own. See our guide on positional talipes versus clubfoot for the differences.
Q: I smoked early in pregnancy before I knew I was pregnant. Has this harmed my baby?
A: The risk from smoking is dose-dependent and relates to sustained exposure. Brief exposure in very early pregnancy carries a much smaller risk than continued smoking throughout. The best thing you can do now is stop smoking — your midwife can refer you to free NHS support. Try not to blame yourself; many women do not realise they are pregnant immediately.
Q: Should I have genetic testing if there is clubfoot in my family?
A: There is currently no clinical genetic test to predict isolated clubfoot. Genetic testing during pregnancy (such as amniocentesis or CVS) is typically offered when clubfoot is detected alongside other anomalies that might suggest a chromosomal condition. For isolated clubfoot in families, genetic counselling can help you understand recurrence risks without invasive testing.