Pregnancy and Return to Sport

Blood volume and cardiac output rise, resting heart rate climbs, and the heart rate response to a given workload shifts, which is why heart rate targets become unreliable in pregnancy and intensity is better judged by rating of perceived exertion (RPE) or the talk test. Ventilation increases, and breathlessness at loads that were previously comfortable is expected rather than alarming.

Mechanically, the centre of mass moves forward and upward as the uterus grows, the base of support widens, and balance is harder, which matters more for the risk of falling than for anything else. Ligamentous laxity increases, although the link between relaxin and injury is considerably weaker than it is usually assumed to be, and it should not be used to justify blanket restriction. Thermoregulation and hydration demands change, and as pregnancy advances the uterus can compress the inferior vena cava in supine positions, reducing venous return.

None of this argues against training. It argues for adapting how intensity is judged, how balance-dependent activities are chosen, and how the athlete positions herself.

The UK Chief Medical Officers advise at least 150 minutes of moderate intensity activity every week throughout pregnancy, with muscle strengthening twice per week. The framing is deliberately permissive: if you are not active, start gradually, and if you are already active, keep going. Every activity counts, every minute counts, more is better, and there is no evidence of harm. There is no minimum bout length. Listen to your body and adapt. Do not bump the bump.

Intensity is judged by conversation rather than by a number, and NHS advice puts it well: a pregnant woman should be able to hold a conversation while exercising, and becoming breathless while talking suggests she is working too hard.

What to avoid is narrower than is commonly assumed. NHS advice is to keep up normal activity, including sport and running, for as long as it feels comfortable, so there is no general prohibition on impact for an experienced runner. Contact sports carrying a risk of being hit, such as kickboxing, judo and squash, are avoided. Activities with a risk of falling, such as horse riding, downhill skiing, ice hockey, gymnastics and cycling, are approached with caution rather than banned, since the fall is the hazard. Lying flat on the back for long periods is avoided, particularly after 16 weeks. Scuba diving is avoided, because the fetus has no protection against decompression sickness, and exercise above 2,500 metres is avoided because of the risk of altitude sickness. Someone who was inactive before pregnancy does not suddenly take up strenuous exercise. Pelvic floor exercises are recommended for all pregnant women, advice that comes from the NHS rather than from the physical activity guidance.

Some conditions need individual obstetric assessment before an exercise plan is agreed, rather than a rule applied from a list. They include significant cardiac or restrictive lung disease, cervical incompetence or cerclage, persistent second or third trimester bleeding, placenta praevia in later pregnancy, preterm labour, ruptured membranes, pre-eclampsia, severe anaemia, poorly controlled hypertension or type 1 diabetes, and fetal growth restriction. For the elite athlete continuing high-volume, high-intensity training, the evidence base is thin, so decisions are individualised and shared with the obstetric team.

For examination purposes it helps to hold the contraindications as two separate lists rather than as a single body of caution. The absolute contraindications are a defined list including haemodynamically significant heart disease, restrictive lung disease, an incompetent cervix or cerclage, multiple gestation at risk of premature labour, persistent second or third trimester bleeding, placenta praevia after 26 weeks, premature labour in the current pregnancy, ruptured membranes, pre-eclampsia or pregnancy-induced hypertension, and severe anaemia. Relative contraindications permit modified activity with closer review. Alongside both sits a third category, the reasons to stop immediately: vaginal bleeding, regular painful contractions, fluid leakage, breathlessness before exertion, dizziness, headache, chest pain, muscle weakness affecting balance, or calf pain and swelling. From around 16 weeks, prolonged supine exercise is avoided because of aortocaval compression by the gravid uterus.

Treating the six-week postnatal check as permission to resume impact training is a common error in this population, and it is worth saying so plainly to athlete and coach. UK guidance covers birth to 12 months, again recommending at least 150 minutes of moderate intensity activity a week, alongside pelvic floor exercises and a gradual approach.

Every athlete is screened for symptoms: urinary or faecal incontinence, a sense of heaviness or dragging in the pelvis, and pain. Any of these warrants assessment by a specialist pelvic health physiotherapist, as does an elite or high-load return, a complicated delivery, or an athlete who is simply worried. A visible or palpable gap along the midline suggesting diastasis rectus abdominis (DRA) is a finding rather than a diagnosis, and the width of the gap alone, in an athlete with no symptoms and good function, is not by itself a reason to refer.

Before running, a widely used expert-opinion screen asks the athlete to manage a 30-minute walk, single leg balance, a single leg squat, jogging on the spot, forward bounds, hops and the single leg running man, all without leaking, heaviness, dragging or pain. It is a sensible structured way to load the system and watch for symptoms, but it has not been validated, so it informs the conversation rather than issuing a certificate. Failing an item is a reason to build capacity and retest, not a reason to stop.

Timing is individualised. Widely used UK guidance suggests low-impact work in the early months and running from around three to six months postnatal, which remains a useful benchmark, particularly after caesarean section. A later international consensus is clearer that readiness is symptom-guided, individualised and multidisciplinary rather than dictated by a date, and a well-supported, asymptomatic athlete with good capacity may reasonably run earlier. The criteria decide; the calendar informs.

Readiness is also more than the pelvic floor. Sleep, fatigue, mood, social support, energy availability and lactation all shape what an athlete can tolerate, and a plan that ignores them fails for reasons that have nothing to do with tissue. Breastfeeding raises energy demand, so energy availability is restored deliberately rather than left to chance. Iron studies are not needed routinely, but a full blood count and ferritin are checked where symptoms or risk factors suggest iron deficiency, such as fatigue out of keeping with the training, blood loss at delivery, or heavy periods. Exercise does not meaningfully affect milk supply or composition. Progression then runs from run-walk, to continuous running, to sport-specific loading, with symptoms as the guide throughout.

• •The UK Chief Medical Officers' physical activity guidance, published in 2019, covers pregnancy and the postpartum year, with the intensity and strengthening recommendations, the every-minute-counts framing and the safety messages.
• •NHS advice on exercise in pregnancy supplies the talk test, the activities to approach with caution, the specific things to avoid, and the pelvic floor recommendation.
• •The returning to running postnatal guidelines by Goom, Donnelly and Brockwell set out the pelvic health assessment, an expert-opinion load and impact screen and the three to six month benchmark.
• •A later international Delphi consensus on return-to-running readiness after childbirth emphasises criteria-based, symptom-guided and individualised decisions over fixed timelines.

• •The guidance is at least 150 minutes a week with strengthening twice weekly, and every minute counts, with no minimum bout.
• •Heart rate targets are unreliable in pregnancy, so use rating of perceived exertion or the talk test.
• •Keep going for as long as it feels comfortable: there is no general ban on impact for an experienced athlete.
• •Avoid contact sports, prolonged supine after 16 weeks, scuba diving and exercise above 2,500 metres; take care with fall risk.
• •The six-week postnatal check is not clearance for impact training.
• •Readiness to return is criteria-based and symptom-guided, not a date, and covers sleep, mood, energy and support.