How to Exercise Safely Through Pregnancy: Trimester-by-Trimester Guidance, Sample Routines, and Warning Signs

Table of Contents

1. Key Highlights
2. Introduction
3. Why exercise matters during pregnancy
4. How pregnancy changes the rules for movement
5. Trimester-by-trimester blueprint: what to do and what to avoid
6. Core and pelvic-floor training without increasing risk of diastasis recti
7. Cardio: intensity, talk test, and heart rate guidance
8. Strength training: progression, breathing, and load management
9. Pregnancy modifications for common activities
10. Recognizing red flags: when to stop and seek care
11. Practical daily guidelines: hydration, temperature, and recovery
12. Sample trimester-specific training plans
13. Preparing for labor: functional conditioning and breathing
14. Addressing common concerns and myths
15. When to seek professional support beyond your prenatal provider
16. Real-world case studies: adaptations that work
17. Practical equipment and class options
18. Legal and workplace considerations for exercising while pregnant
19. The transition to postpartum: continuity and timing
20. FAQ

Key Highlights

• Exercise during pregnancy is generally safe and beneficial when adapted for each trimester; aim for about 150 minutes of moderate aerobic activity weekly unless contraindicated.
• Modify workouts as your body changes: avoid supine positions after the first trimester, prioritize low-impact cardio and pelvic-floor/core-safe strength work, and stop immediately for warning signs such as bleeding, severe dizziness, or decreased fetal movement.
• Practical, trimester-specific routines and technique cues reduce injury risk and prepare the body for labor; consult your healthcare provider about individualized restrictions.

Introduction

Pregnancy rearranges nearly every system in the body: hormones loosen connective tissue, blood volume and cardiac output increase, and the center of gravity shifts forward with a growing uterus. That combination produces new strengths and new vulnerabilities. For most pregnant people, continuing to move is not only possible but advisable—exercise reduces common complaints like back pain, lowers the risk of gestational diabetes and excessive weight gain, and supports mood and endurance for labor.

The key is precision. What counted as a safe workout before pregnancy may require modification. Intensity, posture, exercise selection, and recovery all deserve recalibration across trimesters. The guidance that follows combines practical biomechanics, simple clinical rules of thumb, and real-world examples so you can maintain fitness while protecting maternal and fetal health.

Why exercise matters during pregnancy

Exercise during pregnancy delivers benefits across physical and emotional domains:

• Cardiometabolic health: Regular moderate activity reduces the likelihood of gestational diabetes and helps control weight gain. Organizations such as the American College of Obstetricians and Gynecologists recommend 150 minutes of moderate-intensity aerobic activity per week in the absence of medical contraindications.
• Musculoskeletal resilience: Strength work targeted at the posterior chain, hips, and pelvic floor reduces low-back pain and can improve functional mobility late in pregnancy and into postpartum recovery.
• Labor preparedness: Aerobic conditioning and pelvic-floor control can improve stamina, reduce the perception of effort during labor, and contribute to smoother recovery.
• Mental health: Exercise decreases anxiety and depressive symptoms for many pregnant people and supports sleep quality.

These advantages do not remove the need for individual assessment. Pregestational conditions (e.g., significant cardiac disease, restrictive lung disease, certain cervical insufficiencies) or obstetric complications (e.g., placenta previa after 26 weeks with bleeding, preeclampsia) may change recommendations. Routine prenatal visits are the right time to confirm whether exercise goals should be adjusted.

How pregnancy changes the rules for movement

Hormonal changes—principally rising relaxin and progesterone—loosen ligaments and reduce joint stability. That makes the ankles, knees, and pelvis more susceptible to sprain and strain. Simultaneously, increased blood volume and cardiac output raise demands on the cardiovascular system, and a growing uterus moves the center of mass forward, altering balance and gait.

Practically:

• Avoid activities with a high fall risk (alpine skiing, horseback riding, contact sports) as pregnancy advances.
• After the first trimester, avoid sustained supine exercises—lying flat on the back can compress the inferior vena cava and reduce venous return, causing dizziness and decreased uterine blood flow.
• Use perceived exertion and the talk test rather than rigid heart rate targets, because pulse responses to exercise vary widely in pregnancy.

Understanding these physiological shifts explains why some common-sense changes—lowering intensity, favoring low-impact cardio, and protecting the pelvic floor—are not arbitrary but protective.

Trimester-by-trimester blueprint: what to do and what to avoid

Each trimester presents distinct goals and constraints. The following blueprint offers safe options, examples, and progressions.

First trimester: listening and adaptation Goals: Maintain baseline fitness, preserve energy, avoid overheating. What to do

• Keep doing what you did before pregnancy if it felt comfortable, but reduce intensity when fatigued or nauseated.
• Prioritize light-to-moderate aerobic work (brisk walking, easy cycling), gentle strength training with good technique, and mobility that relieves tension.
• Hydrate frequently; even mild dehydration can cause uterine contractions or dizziness. Example session (30–40 minutes)
• 5–10 minute brisk walk warm-up.
• 20 minutes of moderate-intensity cycling or treadmill walking (talk test: you can speak in short sentences).
• 2 sets of 10–12 squats, glute bridges, and single-arm rows with light-to-moderate weight or resistance band, focusing on controlled tempo.
• Gentle stretching and diaphragmatic breathing cooldown. What to avoid
• Prolonged high-heat environments; stop hot yoga and saunas early in pregnancy.
• Pushing through severe nausea, faintness, or pain. Those are signals to reduce or stop activity and check with your provider.

Second trimester: finding stable strength and balance Goals: Build or maintain cardiovascular endurance, strengthen hip and pelvic stabilizers, and protect the core for changing mechanics. What to do

• Emphasize low-impact cardio (swimming, stationary cycling, elliptical) because joint laxity increases injury risk.
• Incorporate posterior-chain strength (deadlift variations, Romanian deadlifts with light weight, hip hinges) and lateral hip work (clamshells, side steps) to stabilize the pelvis and lower back.
• Work the pelvic floor with gentle contractions and breath-synchronized practice. Begin to retrain the transverse abdominis with safe core activation cues. Example session (40–50 minutes)
• 8–10 minute swim or water walking warm-up, or brisk walking.
• Strength circuit: 3 rounds of 10–12 goblet squats, 8–10 single-leg RDLs (bodyweight or light dumbbell), 15–20 banded lateral walks, 10–12 supported rows.
• 3 sets of pelvic-tilt progressions and gentle anti-diastasis core work (see next section).
• 5–10 minute relaxation breathing and hip mobility. Modifications and cues
• Avoid supine position for extended periods. Use incline back support or perform exercises seated or side-lying after approximately 12–20 weeks depending on comfort.
• Keep loads moderate—focus on movement quality, not maximal lifts. What to avoid
• Heavy, uncontrolled lifts or Valsalva-style breath-holding during exertion.
• Dynamic twisting with heavy loads that may encourage abdominal doming.

Third trimester: conserving energy and preparing for labor Goals: Maintain mobility, pelvic function, and low-level conditioning; reduce discomfort and conserve energy for labor. What to do

• Shorter, more frequent sessions often outperform long workouts. Walks, water exercise, and pregnancy-tailored yoga maintain mobility without exhaustion.
• Focus on posture, hip flexor stretches, glute strengthening, and pelvic-floor coordination.
• Practice positions and breath patterns used in labor (upright supported squat, side-lying release, slow exhalation with bearing-down simulations under provider guidance). Example session (20–35 minutes)
• 10–15 minute easy stationary cycling or water walking.
• 2 rounds of 10 supported bodyweight squats to a chair; 12 seated rows with resistance band; 10 hip extensions on hands-and-knees.
• 3–5 minutes of pelvic-floor engagement drills: gentle contraction-release sequences with diaphragmatic breathing.
• Finish with a supine-to-side-to-seated controlled transition to practice getting up safely. Modifications and cues
• Prioritize sitting and side-lying options for strength and mat work.
• Use wider base of support for balance: staggered stance in lunges, wide squat stance. What to avoid
• Exercises that require quick changes in direction or risk a fall.
• Long-duration high-intensity intervals that leave you breathless and unable to speak comfortably.

Core and pelvic-floor training without increasing risk of diastasis recti

Diastasis recti—separation of the rectus abdominis—is common in pregnancy and demands careful exercise selection to avoid aggravation.

Avoid

• Traditional sit-ups, full upright crunches, and intense planks that produce a visible doming or coning of the midline with exertion.
• Heavy loaded axial flexion that increases intra-abdominal pressure without proper support.

Prefer

• Transverse abdominis activation: draw the belly button gently toward the spine while maintaining normal breathing and an upright posture. Integrate into activities rather than isolate as a static hold.
• Modified core strength: heel slides (small range), dead bug progressions with minimal lumbar movement, side-lying clamshells combined with gentle transverse engagement.
• Functional integration: practice bracing during squats and lifts with an exhale on exertion rather than breath-holding.

Detecting diastasis

• Lie semi-reclined with knees bent, lift the head slightly and feel for a gap along the midline. Gently pressing two fingers into the linea alba will reveal a separation if present. Report concerns to your provider or a pelvic health physical therapist who can measure width and depth and prescribe targeted rehabilitation.

Pelvic-floor training

• Kegels remain useful but require correct technique: a quick test is halting urine midstream once (as a learning cue only—do not perform regularly while voiding). Long, slow contractions of 5–10 seconds followed by equal-length relaxations, repeated in sets throughout the day, build endurance. Quick flicks train fast-twitch response for sudden increases in intra-abdominal pressure.
• Avoid overactivating the pelvic floor; excessive tension can cause pain or urinary retention. A pelvic health specialist can biofeedback training if needed.

Cardio: intensity, talk test, and heart rate guidance

Pregnancy raises resting heart rate and changes cardiac response to exertion. Target heart-rate zones used outside pregnancy are not universally applicable.

Use these practical rules:

• Talk test: Maintain an intensity where you can carry on a conversation comfortably. If you cannot speak in short phrases, reduce intensity.
• Rate of perceived exertion (RPE): Aim for 12–14 on the Borg 6–20 scale for moderate effort—this corresponds to moderate exertion where you feel you are working but sustainable.
• Avoid maximal-effort sprints and long exposures at high intensity, particularly if you were not training at that level before pregnancy.
• When clearing heart-rate targets from a provider, treat them conservatively and monitor how you feel during and after sessions.

Swimming and water-based exercise deserve special mention. Buoyancy reduces axial load, joint stress, and risk of falls. Water exercise also supports venous return, reduces edema, and allows longer-duration, low-impact cardio.

Strength training: progression, breathing, and load management

Strength training during pregnancy improves function and supports labor. Follow these principles:

Load selection and progressions

• Begin with the load that allows you to complete 10–15 controlled reps with good form. The goal is to maintain strength, not to achieve new personal records.
• Use two to three weekly sessions targeting major muscle groups. Prioritize multiple-joint, functional moves: squats, hip hinges, rows, and push variants adapted to comfort.
• Adjust frequency and volume if recovery slows. In the third trimester, reduce volume, increase rest between sets, and allow an extra recovery day if needed.

Breathing and technique

• Avoid prolonged Valsalva maneuvers. Exhale on effort (lifting or pressing) and inhale on the return.
• Keep a neutral spine and avoid excessive lumbar extension as the pelvis tilts anteriorly with growth of the abdomen.

Safety adaptations

• Replace high-risk moves (heavy cleans, snatches, or high-impact plyometrics) with controlled, lower-risk alternatives.
• Use machines or benches for stability if balance becomes a limiting factor.
• When balance is impaired, train unilateral strength with support (hold onto a stable surface).

Real-world example: a runner's transition A habitual runner at six weeks who develops pelvic girdle soreness may shift to stationary cycling and pool running by 14 weeks. Strength sessions that include hip hinges and single-leg Romanian deadlifts support running mechanics and reduce pelvic strain. When comfortable, treadmill running with reduced pace and softer surfaces may resume in short intervals if cleared.

Pregnancy modifications for common activities

• Running: Continue if asymptomatic and accustomed to it pre-pregnancy. Reduce pace, lengthen step to reduce pelvic load, and opt for softer surfaces. Stop with pelvic girdle pain or vaginal bleeding.
• Cycling: Stationary cycling is low-risk throughout pregnancy. Outdoor cycling carries fall risk; swap to indoor bikes in later trimesters.
• Swimming: One of the safest aerobic choices; buoyancy relieves joint load and reduces overheating.
• Yoga and Pilates: Prenatal classes designed for pregnancy are preferable. Avoid deep twists, strong backbends, and poses requiring balance without support. Skip inversions and wide-open chest work that strain the upper back unless the teacher is experienced in prenatal adaptations.
• Weightlifting: Continue with adjustments. Skip max-effort lifts, prefer higher reps and lower loads, and maintain stable footing and breathing patterns.
• High-intensity interval training (HIIT): Can be performed at moderate intensity if the individual was accustomed before pregnancy, but intervals should remain short and recovery ample. Favor low-impact intervals (rower, bike, elliptical) over jumping or sprints.

Recognizing red flags: when to stop and seek care

Immediate cessation of activity and contact with your healthcare provider should follow any of these symptoms:

• Vaginal bleeding or fluid leakage.
• Regular painful contractions before 37 weeks.
• Sudden, severe abdominal pain.
• Dizziness, fainting, or severe shortness of breath (unable to maintain conversation).
• Chest pain or palpitations that feel abnormal or severe.
• A sudden decrease in fetal movement after 28 weeks.
• Severe headache, visual changes, or sudden swelling—symptoms that can indicate hypertensive disorders.

If any exercise produces these signs, stop, lie on your left side if possible (to optimize venous return), hydrate, and call your clinician for guidance.

Practical daily guidelines: hydration, temperature, and recovery

Hydration: Drink before, during, and after exercise. Thirst lags behind dehydration; sip often. For sessions longer than 45–60 minutes, consider a carbohydrate-electrolyte beverage if tolerated.

Temperature: Avoid overheating, particularly in the first trimester. Dress in breathable layers, exercise in a cool environment, and avoid hot tubs and saunas.

Recovery: Sleep, nutrition, and stress reduction are critical. Pregnancy raises caloric demands modestly—most prenatal calories should come from nutrient-dense sources: lean protein, whole grains, healthy fats, fruits, and vegetables. Allow extra recovery time when fatigue increases and schedule rest days.

Monitoring recovery

• Track resting heart rate and sleep quality. If resting heart rate is persistently elevated and recovery poor, scale back training.
• Use subjective measures: increased soreness, poor sleep, or mood changes are valid reasons to reduce volume or intensity.

Sample trimester-specific training plans

These sample plans assume an uncomplicated pregnancy in a person who exercised prior to pregnancy. Modify frequency and intensity based on fitness level and clinical guidance.

First-trimester sample week (total ~150 minutes)

• Monday: 30-minute brisk walk + 10 minutes mobility and diaphragmatic breathing.
• Wednesday: 30-minute light resistance session (2 sets of 12 reps each: goblet squat, banded row, glute bridge, standing single-arm press) + pelvic-floor practice.
• Friday: 40-minute swim or stationary bike at moderate pace.
• Sunday: 20–30 minutes prenatal yoga focusing on hip opening and thoracic mobility.

Second-trimester sample week (maintain 150–180 minutes)

• Monday: 30-minute elliptical or cycle intervals (5 x 2 minutes moderate/2 minutes easy).
• Tuesday: Strength session (3 rounds: 12 goblet squats, 10 single-leg RDLs, 15 banded lateral walks, 12 seated rows) + core activation.
• Thursday: 40-minute swim including 20 minutes continuous moderate effort.
• Saturday: 30-minute brisk walk with post-walk hip and lower back stretching.

Third-trimester sample week (shorter sessions, higher frequency)

• Monday: 20-minute walk + pelvic-tilt and breathing drills.
• Tuesday: 25-minute water aerobics or pool walking.
• Thursday: 20-minute resistance circuit: chair-supported squats, side-lying hip abductions, elastic band rows, and modified farmer carries.
• Daily: short pelvic-floor sets (3 × 8 long holds at 5–10 seconds, plus quick flicks) and mobility work to ease hip flexors.

These templates emphasize maintenance, not performance. Expect adjustments as the pregnancy progresses.

Preparing for labor: functional conditioning and breathing

Functional conditioning improves the ability to adopt and hold labor positions and to push effectively.

Position-specific training

• Supported squats (holding onto a rack or partner) build hip-opening range and endurance for second-stage labor positions.
• Side-lying hip openers and pelvic-rocking on hands-and-knees ease sacroiliac discomfort and can be used as coping positions during labor.
• Upright walking and stair stepping build stamina for prolonged labor.

Breathing and bearing-down practice

• Practice slow, extended exhales to simulate the pushing phase, coordinating abdominal engagement with breath under a clinician’s guidance.
• Avoid habitual breath-holding. Controlled exhalation reduces intra-abdominal pressure surges and supports oxygenation.

Working with professionals

• Consider prenatal physical therapy for pelvis-related pain and pelvic-floor specialists for complex dysfunction.
• Childbirth education that integrates breath control, positions, and active labor strategies complements fitness preparation.

Addressing common concerns and myths

Myth: Exercise will deprive the baby of nutrients/oxygen

• Moderate exercise does not reduce fetal oxygenation in healthy pregnancies. Transient changes in uterine blood flow during exercise are compensated for by maternal cardiovascular responses. Persistent concerns should prompt medical evaluation.

Myth: Lifting weights causes miscarriage

• There is no evidence that appropriate resistance training causes miscarriage in uncomplicated pregnancies. Avoid maximal lifts and breath-holding, and stop if bleeding or pain occurs.

Question: Is pelvic pain normal when exercising?

• Some pelvic discomfort related to increased ligament laxity is common, especially in the second trimester. Pain that is sharp, unilateral, or associated with instability warrants assessment by a clinician or pelvic health physiotherapist.

Myth: If I wasn't active before pregnancy, I should wait until postpartum to start

• Initiating light-to-moderate exercise during pregnancy is safe for many previously inactive individuals after medical clearance. Gentle walking, water exercise, and supervised low-load strength work are appropriate starting points.

When to seek professional support beyond your prenatal provider

• Significant pelvic girdle pain, symphysis pubis dysfunction, or pelvic-floor pain benefit from a pelvic health physical therapist.
• Persistent urinary incontinence, painful intercourse, or large diastasis recti measurements benefit from specialized rehabilitation.
• Cardiopulmonary symptoms (shortness of breath at rest, chest pain) require urgent medical attention.

A prenatal exercise specialist or certified prenatal fitness instructor can help tailor progressions and ensure safe technique.

Real-world case studies: adaptations that work

Case 1: The recreational runner Background: 32-year-old runner, 20 miles/week before pregnancy, develops mild pelvic pain at 14 weeks. Adaptation: Switched to elliptical and pool running for low-impact cardio. Strength program twice weekly emphasized single-leg deadlifts and glute strengthening for pelvic stability. Maintained shorter runs on soft surfaces with reduced mileage; successfully continued running intermittently into the second trimester without complications.

Case 2: The weightlifter Background: 36-year-old who coached and trained with heavy barbell lifts pre-pregnancy. Adaptation: Maintained three weekly strength sessions but dropped to submaximal loads (60–70% of previous working weights) with increased reps, emphasized tempo and bracing cues, substituted barbell back squats for goblet or trap-bar squats to reduce supine and balance demands. Avoided maximal attempts and heavy overhead work after 20 weeks. Reported maintained strength, reduced low-back discomfort, and easier postpartum return.

Case 3: The previously sedentary patient Background: 28-year-old sedentary, has uncomplicated pregnancy at 16 weeks. Adaptation: Cleared by provider, initiated walking program (20–30 minutes, most days), introduced twice-weekly bodyweight strength sessions (squats, rows, hip bridges), and pelvic-floor education. Improved fatigue and mood and avoided excessive gestational weight gain.

Each case demonstrates adaptation rather than complete cessation—tailored progression preserved physical capacity while prioritizing safety.

Practical equipment and class options

• Stationary bike or elliptical: Low-risk cardio with minimal fall risk.
• Resistance bands and dumbbells: Versatile for progressive strength without excessive load on joints or balance.
• Prenatal fitness classes: Seek instructors with prenatal certifications; avoid general high-intensity group classes without prenatal modifications.
• Pool or aquatic classes: Provide low-impact conditioning and can be especially helpful in late pregnancy.

When choosing a class or trainer, ask about their experience with pregnancy modifications and how they adapt for pelvic pain, balance changes, and diastasis recti.

Legal and workplace considerations for exercising while pregnant

Workplace physical duty may require modifications during pregnancy. Provide documentation from your clinician if you require temporary adjustments to heavy lifting, prolonged standing, or hazardous work. Employers often accommodate reasonable modifications as part of occupational health protocols.

For fitness professionals, liability considerations exist when training pregnant clients. Obtain appropriate certifications and screen clients using a pregnancy-focused intake that records obstetric history and any contraindications.

The transition to postpartum: continuity and timing

Postpartum return to exercise depends on delivery mode, healing, and individual recovery. General timelines:

• Immediate postpartum (first 6 weeks): Focus on gentle walking, pelvic-floor activation, and controlled breathing. Avoid heavy lifting and high-impact activities until cleared.
• After 6 weeks: With clinician approval, gradually reintroduce strength training and moderate cardiovascular work. Cesarean births generally require a more cautious return due to abdominal incision healing.
• Pelvic-floor dysfunction or persistent diastasis recti: Seek pelvic health PT before advancing intensity.

Practical cues for safe return

• Begin with bodyweight movements and progress when core control and pelvic-floor function are restored.
• Continue pelvic-floor sets and functional core integration for lifting infants and performing household tasks.

FAQ

Q: How much exercise should I aim for during pregnancy? A: The general recommendation is 150 minutes of moderate-intensity aerobic activity per week, spread across most days. Strength training two times per week targeting major muscle groups is appropriate for most people. Tailor volume based on baseline fitness and medical guidance.

Q: Can I continue running during pregnancy? A: Running is acceptable for many who were habitual runners pre-pregnancy, provided there is no bleeding, pelvic instability, or other contraindication. Reduce pace and distance as needed, switch to lower-impact options if pelvic pain or balance issues arise, and prioritize soft surfaces.

Q: When should I stop exercising and contact my provider? A: Stop and seek care for vaginal bleeding, fluid leakage, regular contractions before 37 weeks, sudden severe pain, fainting, chest pain, severe shortness of breath, or sudden decrease in fetal movement.

Q: Is it safe to lift weights while pregnant? A: Yes, with modifications. Avoid maximal lifts and breath-holding. Use moderate loads, prioritizing controlled tempo and technique. Switch to safer variants (trap-bar deadlifts instead of heavy back squats) when balance or belly size limits safe mechanics.

Q: How do I avoid or manage diastasis recti? A: Avoid intense anterior crunches and heavy-loaded flexion. Train the transverse abdominis with gentle activation, integrate core bracing into functional lifts, and consult a pelvic health physical therapist if separation is suspected.

Q: Can I do high-intensity interval training (HIIT)? A: Short, controlled HIIT sessions can be acceptable for those accustomed to high-intensity training before pregnancy. Prefer low-impact modalities and reduce interval length and intensity as pregnancy progresses. Use the talk test to gauge effort.

Q: Is yoga safe during pregnancy? A: Prenatal yoga is safe and beneficial when taught by instructors experienced in pregnancy. Avoid deep backbends, strong abdominal work, prolonged supine positions after early pregnancy, and unsupported balance poses.

Q: What exercises help prepare for labor? A: Upright squats, supported lunges, pelvic-tilt and rocking patterns on hands-and-knees, and endurance-building walking or cycling support labor stamina. Practice breath patterns and efficient pushing mechanics with clinician guidance.

Q: How soon after delivery can I resume exercise? A: Many can begin gentle walking and pelvic-floor activation soon after vaginal delivery, but return to higher-intensity work typically waits until a 6-week postpartum check (longer if cesarean). Individual healing rates vary; seek personalized clearance.

Q: Should I monitor my heart rate during exercise? A: Heart-rate monitoring is optional. Perceived exertion and the talk test are reliable guides because heart-rate responses vary in pregnancy. If using heart-rate targets, do so conservatively and in coordination with your provider.

Q: When is exercise not recommended? A: Certain conditions are absolute or relative contraindications: significant heart or lung disease, incompetent cervix, multiple gestation at risk of preterm labor, persistent bleeding, preeclampsia, or severe anemia. Always consult your healthcare provider.

Q: Who should I see for specialized help? A: Seek a pelvic health physical therapist for pelvic pain, dysfunction, or diastasis recti. Consult a certified prenatal exercise specialist for tailored programming. Your obstetric provider is the primary point for medical clearance and pregnancy-specific concerns.

Maintaining fitness throughout pregnancy improves many aspects of maternal health and creates a stronger platform for labor and recovery. The safest programs respect the evolving biomechanics of pregnancy, prioritize controlled strength and low-impact cardiovascular work, and stop when red flags appear. Work with your healthcare team and qualified trainers to build a plan that protects you and your baby while keeping movement an empowering part of pregnancy.