Methodological characteristics, samples, quality and characteristics of the interventions/training patterns of the included studies
| Reference | Study design | SE | Sample | QA | Intervention/training patterns during/after pregnancy | Comparators |
| Almquist et al 52 | Case report | (a) | n=1 | g | ET and ST 4.2–6.9 hours/week prepregnancy, structured training during pregnancy, Week 1: 4 moderate-intensity interval training sessions (4×12 min); Week 2: 3–6 low-intensity training sessions (>60 min continuous cycling); :Week 3: 4 high-intensity interval training sessions (5×5 min); Week 4: recovery week, max. >20 hours/week at 18 weeks of pregnancy. | None |
| Beilock et al54 | Retrospective observational cohort (QNR) | (a) | n=26 age=30.65; competitive athletes (swimmers 41%, track and field/road racing 29%) | f | 49% decreased participation in cardiovascular and resistance exercise during the first trimester, 72% during the second and 80% during the third. | None |
| Bo et al48 | Retrospective case–control study (QNR) | (a) | n=31 elite athletes (various types of sports) (response rate 77.5%) | f | Elite athletes’ sport volume: 14 hours/week before, 4 hours/week 6 weeks postpartum, 10.8 hours/week when filling out QNR; 38% started jogging within 6 weeks postpartum, 4.3% control; 77% of elite athletes continued to compete at the same level after childbirth and 45% were still at this level when answering the QNR. | n=46 age-matched controls (response rate 57.7%), age=34 years |
| Bubnjević et al53 | Case report | (a) | n=1 (marathon runner), age=33 years | f | During third trimester, reduction in the number of training sessions/week and the length of the runs; at 7 months, 6 sessions/week 7 km each; at 8 months, 5 km five times a week; at 9 months, 5 km four times a week; pace 4.30–6.15 km/hour. | None |
| Bung et al 43 | Case report | (a), (b) | n=1 (competitive sports for 12 years, recently 400 m running), age=25 years | f | Training six times a week conditioning and performance (gymnastics/stretching, several sprints, running out, relaxation); during pregnancy focus on ET and ST; 24th pregnancy week, 28th week and then every 2 weeks, during puerperium, 6 weeks and 6 months postpartum: bicycle-ergometer testing up to 150 bpm mHR and running on a track (warming up, three 200 m and one 100 m sprint); <6 months after delivery personal records in various short-distance runs. | None |
| Darroch et al56 | Retrospective observational cohort (QNR) | (a) | n=42 (elite, world-class runners) age=31.7±3.8 years | g | 9±2 running sessions/week, running volume decreased from 63±34 km/week (first trimester) to 30±30 km/week (third trimester); significantly lower average training pace, return to activity/exercise at 6 weeks postpartum and to 80% of prepregnancy training volumes by 3 months. | None |
| Davies et al44 | Case report | (a), (b) | n=1 (marathon runner), age=33 years | g | Prior to conception: 155 km/week, 140–180 mHR; during pregnancy 107±19 km/week, 130–140 mHR; road and cross-country race first+second trimester; moderate cycling exercise was resumed 8 days postpartum; return to competitive racing 8.5 weeks postpartum; standardised submaximal field running test weekly during the first 32 weeks of pregnancy: three repetitions of 2.5 km road runs at a velocity HR of 140 mHR, 150 mHR, 160 mHR, separated by a 3 min recovery jog; standardised submaximal treadmill test 29 weeks antepartum and 10 weeks postpartum: four incremental stages (4 min), 30 s break (blood lactate), running velocities 3.33–4.17 m/s. | None |
| Drastig et al60 | Retrospective observational cohort (QNR) | (c) | n=32 (sport climbing), age=31 years; drop out=1; partly missing data n=17 | f | Sport climbing partly top ranking before pregnancy; climbing experience before pregnancy 2–24 years, skill level before pregnancy 4–7 (UIAA scale=International Climbing and Mountaineering Federation). 50% climbed until the 36th week; 90% adjusted climbing habits (reducing climbing difficulty, doing more top roping). | None |
| Kardel et al47 | Controlled intervention | (a) | n=42 (biathlon, bicycling, marathon; some at national and international levels); HEG n=20, age 28.8 years; MEG n=21, age 26.7 years drop out n=1, missing data n=9 | p | HEG preconception: 8.2 hours/week; intervention: 8.6 hours/week; muscle ST 72 min two times a week, interval training 35 min two times a week mHR 170–180/min and ET 2.5 hours two times a week mHR 120–140/min), 1 woman stopped training 7 days before labour, 8 stopped 1–3 days before and 7 women exercised the day before labour. | MEG preconception: 4.8 hours/week; intervention: 6.2 hours/week (muscle ST 72 min two times a week; interval training 25 min two times a week mHR 170–180/min; ET 1.5 hours two times a week mHR 120–140/min), 1 woman stopped training 5 days before labour, 12 stopped 1 to 4 days before and 3 exercised the day before labour |
| Penttinen et al49 | Retrospective case–control study (QNR) | (a) | n=30 (endurance athletes, national top-level cross-country skiing, running, speed-skating or orienteering), age 28.1 years; missing data n=3 | p | Postpartum: 18 athletes continued to compete, the median interval being 8.2 months (range 2–24 months). Two (11%) achieved better condition than before the pregnancy, 11 (61%) reached the same level and 5 (28%) did not achieve the same performance level. | Controls (next primipara in the diaries formed a member of the control group) n=30; cave: no matched controls |
| Salvesen et al58 | Controlled intervention | (b) | n=6 (cross-country skiing, duathlon, long-distance running, race walking), age=28–37 years | p | Prior to conception 15–22 hours training/week; testing at 23–29 weeks of pregnancy; 10 min warm-up mHR 135 bpm; 3–5 submaximal workloads (5 min each) on a treadmill with 60%–90% of VO2max; 4-min pause (sampling capillary blood lactate concentration, ultrasound assessments of the maternal–fetal circulation). | None |
| Solli et al25 | Case report | (a) | n=1 (cross-country skier), age=34.5–36.8 years | g | Average training volume during pregnancy 14 hours/week, which included 79%, 86% and 49% of prepregnancy volumes during the first, second and third trimester; testing first, second trimester and postpartum. | None |
| Sigurdar-dottir et al50 | Retrospective case–control study | (a) | n=41 (low impact group: swimming, golf, riding/jockey, weightlifting, ballroom dancing, motocross, pole fitness); n=89 (high impact group: track and field, football, basketball, cross fit, team gymnastics, handball, racket sports, self-defence sport); missing data n=45 | f | Training during pregnancy: low impact 10.2 hours/week, high impact 8.5 hours/week. | n=118 non-athletic group (not compete in sports, physically active at recreational level); training during pregnancy 0.2 hours/week |
| Sundgot-Borgen et al51 | Case–control study | (a) | n=34 (elite athletes at international level; endurance, ball sports, aesthetic, weight or technical), age=33.1 years | f | ET prepregnancy 750 min/week, during pregnancy ~600–700 min/week, ST prepregnancy ~115 min/week, during pregnancy ~55–85 min/week. | n=34 regular active (>150 min/week) but not at an international level age=31.5 years; ET prepregnancy ~180 min/week, during pregnancy 150 min/week; ST prepregnancy 20 min/week, during pregnancy ~15 min/week |
| Szymanski et al59 | Controlled intervention | (b) | n=15 (highly active, predominantly runners), age=32.9 years | f | Vigorous activity >4 days/week; peak treadmill test to volitional fatigue; gestational age 30.3±1.0. | n=15 (regular active: >20 min per session±3 sessions/week), age=34.3 years, gestational age=30.2±0.9; n=15 (non-exercisers) age=32.9 years, gestational age 30.7±1.1; peak treadmill test to volitional fatigue |
| Szymanski et al57 | Controlled intervention | (b) | n=15 (highly active, predominantly runners), age=32.9 years | f | Vigorous activity >4 days/week; peak treadmill test to volitional fatigue; 30-min exercise session at moderate intensity on the treadmill (40%–59% of aerobic capacity reserve); target HR were calculated by the HRR method; 30-min vigorous-intensity session (60%–84% of HRR); gestational age 30.3±1.0. | n=15 (regular active: >20 min per session±3 sessions/week), age=34.3 years, gestational age 30.2±0.9; n=15 (non-exercisers) age=32.9 years, gestational age 30.7±1.1; peak treadmill test to volitional fatigue |
(a) Continuous exercise exposure, (b) acute exposure to intensive activity (performance testing) and (c) high-risk sports.
bpm, beats per minute; ET, endurance training; f, fair; g, good; HEG, high-exercise group; HR, heart rate; HRR, heart rate reserve; MEG, medium-exercise group; mHR, maternal heart rate; p, poor; QA, quality assessment; QNR, questionnaire; SE, type of sports exposure; ST, strength training; VO2max, maximal oxygen consumption.