Historically and traditionally, the recommendations related to physical exercise during pregnancy have been based more on moral or cultural issues than on scientific evidence. During some phases of history, pregnancy has meant a period of seclusion for women (not only physical). One of the adverse consequences has been the common recommendation of rest as a general rule for pregnant women.

Scientific evidence from recent years has achieved a better understanding of the process of pregnancy and childbirth as well as maternal and fetal responses to exercise. Currently, both from a scientific and clinical/obstetric point of view, there is no doubt about the benefits of an active pregnancy for entire body of pregnant woman, and even her child. In fact, risks of a sedentary lifestyle are applicable to the pregnancy situation, even more with important associated complications during pregnancy and postpartum period.

Unfortunately, the impact of COVID-19 has caused an unprecedented global crisis, in this sense the necessary measures taken by the different administrations, especially in terms of confinement causes (from now on) a large number of complications affecting different populations. In summary a complex situation without established prevention strategies exists.

The pregnant population is, due to the nature of the gestation and delivery process, one of the population groups with the highest risk of adverse outcomes and associated complications and whose consequences include the mother, fetus, newborn and even children. According to an important body of scientific literature and based on an epigenetic effect, the intrauterine environment can be a determining factor for the future human being to evolve regardless of complications and pathologies (cardiovascular, metabolic, psychic, emotional). This is demonstrated by numerous recent scientific evidences that confirm the unfortunate association between an adverse intrauterine environment (due to various factors) and observable postnatal pathologies in infants.

In addition, current publications report the large number and variety of alterations that the COVID-19 situation causes in pregnant women and that includes the entire female organism. This complex situation does not only affect aspects of a physical or physiological nature, but also psychic and emotional factors. In summary, a new state of confinement or similar situations in the near future (impossibility of groupings, distance between people), avoid during the daily life of pregnant women one of the important and recent recommendations made by the international scientific community: a pregnancy physically active.

This is especially relevant, due to the dangerous association between complications of a psychological or emotional nature during pregnancy with pre, peri and postnatal disorders (low birth weights, perinatal complications, altered and prolonged deliveries, etc.), which affect not only to the mother and can determine the health of the future human being. According to the scientific literature and based on an epigenetic effect, the intrauterine environment can be a determining aspect in the health of the future human being and the prevention of complications and pathologies (cardiovascular, metabolic, psychic, emotional). This is demonstrated by numerous and recent scientific evidences that confirm the unfortunate association between an adverse intrauterine environment (due to various factors) and different pathologies during and after pregnancy.

It is evident the change that COVID-19 and its effects will generate in the lifestyle of the pregnant population and the increased probability of suffering associated pathologies in the next 24-36 months. No preventive actions have yet been planned in Spain and its public hospitals against the impact of COVID-19 on the quality of life of pregnant women. It is urgent to design and perform an adequate strategy of intervention for its possible prevention. From the scientific point of view, the recommendations are clear and concrete, an aerobic exercise program, designed and supervised by professionals from the Sciences of Physical Activity and Sports, is the best option for pregnant women.

In this sense, in the last 30 years, physical exercise has proven to have many benefits for pregnant women, without causing risks or adverse effects on maternal-fetal well-being. This is confirmed by an important body of scientific literature on gestational physical exercise and its effects on pregnancy outcomes.

Hypothesis Aerobic, moderate, and supervised exercise during pregnancy can be an efficient element of prevention of alterations that the situation generated by COVID-19 causes to the healthy pregnant population and their children.

Objective Examine the influence of a supervised aerobic exercise program during pregnancy, by non-face-to-face and face-to-face ways, on the prevention of maternal, fetal, newborn and infant alterations during the pandemic state and in the near future.

Material and Methods

- Study design.

A randomized clinical trial (RCT) will be carried out, not masked with healthy pregnant women, giving rise to two study groups: exercise group (EG), pregnant women participating in a regular program of supervised physical exercise and control group ( CG), pregnant women who receive normal obstetric monitoring of their pregnancy, including recommendations regarding dietary-nutritional factors, as well as the benefits of an active pregnancy.

All selected pregnant women will sign an Informed Consent before participating in the study.

Women randomly assigned to the CG received general advice from their health care provider about the positive effects of physical activity. Participants in the CG had their usual visits with health care providers during pregnancy, which were equal to the exercise group. Women were not discouraged from exercising on their own. However, women in the CG were asked about their exercise once each trimester using a "Decision Algorithm" (by telephone).

Intervention

General characteristics of the physical exercise program:

• The minimum adherence required will be 80% of the total sessions.
• Onset: gestational week 9-11, immediately after the first prenatal ultrasound, in order to rule out Obstetric Contraindications for physical exercise.
• End: gestational week 38-39.
• Frequency: 3 weekly sessions, various possibilities will be offered at different times from which the pregnant woman can choose, in order to promote work and family conciliation.

Basic Considerations:

1. All the activity carried out will be aerobic.

2. Avoid working positions in which areas normally overloaded by pregnancy are further affected.

3. The work corresponding to flexibility will be carried out always bearing in mind that these are pregnant women, this forces us once again not to include forced operating positions in the exercises or to excessively maintain the stretching times in each area.

4. An adequate fluid intake will be maintained before and after the activity.

5. Also as a general rule and to eliminate potential risks, the following will be avoided:

   • Activities that include the Valsalva maneuver.
   • High ambient temperatures or very humid environments in order to avoid hyperthermia (body temperature higher than 38º C).
   • Sudden movements.
   • Positions of extreme muscular tension.

Structure:

All sessions will begin with a warm-up of 7-8 minutes composed of mild movements and joint mobility of upper and lower limbs exercises. Then a central part of 35-40 minutes, four types of activities will be included (aerobic work, muscle strengthening, coordination/balance tasks, pelvic floor exercises), finally a section of flexibility, relaxation and final talk (comments and sharing) will be performed (12-15 minutes).

Below we offer a greater detail of each part:

I. Warm-up-General activation. Displacements varied without impact activities (avoiding jumps, falls). Mild work of mobility of the main joints.

II. Aerobic section. Exercise to increase intensity up to moderate activities, play with sports equipment (balls, ropes, pikes) or choreographies of different musical styles.

III. Muscle strengthening, general toning exercises of the whole body: lower part (calf, quadriceps, hamstrings, adductors, abductors), upper part (abdominal, pectoral, shoulders, paravertebral musculature). Also exercises for the most weakened and needy muscle groups during pregnancy, the aim is to avoid muscular decompensation.

IV. Coordination and balance exercises: simple tasks of eye-hand and eye-foot coordination with sports equipment, as well as body axis balance exercises.

V. Strengthening the pelvic floor muscles, Kegel exercises will be applied and is basically composed of contractions (slow and fast) of the different structures of the pelvic floor musculature.

VI. Cool down section during 7-8 minutes, aiming to gradually lower the intensity of work with flexibility-stretching and relaxation exercises.

VII. Final Talk. This part is intended for pregnant women to express clearly and openly the sensations and perceptions experienced during the session. The reflection of each participant on the effect of physical practice is sought, not only in the physical or physiological aspect, but also in the psychic and emotional section. The exchange of impressions between the pregnant women, enhances the role of a correctly designed and conducted physical exercise program, as a social mobile of maintenance and improvement of the quality of life of the pregnant woman.

Inclusion Criteria:

• Pregnant women fulfilling the following criteria: >18 years old, singleton pregnancies and planning management and delivery at the research hospitals and also do not participate in any other program of supervised physical exercise.

Exclusion Criteria:

• Women with absolute contraindications. Women with relative contraindications need permission from obstetric care provider prior to participation(1,2):

Absolute contraindications to exercise:

• Ruptured membranes.
• Premature labour.
• Unexplained persistent vaginal bleeding.
• Placenta praevia after 28 weeks' gestation.
• Pre-eclampsia.
• Incompetent cervix.
• Intrauterine growth restriction.
• High-order multiple pregnancy (eg, triplets).
• Uncontrolled type I diabetes.
• Uncontrolled hypertension.
• Uncontrolled thyroid disease.
• Other serious cardiovascular, respiratory or systemic disorder.

Relative contraindications to exercise:

• Recurrent pregnancy loss.
• Gestational hypertension.
• A history of spontaneous preterm birth.
• Mild/moderate cardiovascular or respiratory disease.
• Symptomatic anaemia.
• Malnutrition.
• Eating disorder.
• Twin pregnancy after the 28th week.
• Other significant medical conditions.

References:

1. Mottola, M. F., Davenport, M. H., Ruchat, S. M., Davies, G. A., Poitras, V. J., Gray, C. E., … Zehr, L. 2019 Canadian guideline for physical activity throughout pregnancy. British Journal of Sports Medicine, 2018; 52(21), 1339-1346. https://doi.org/10.1136/bjsports-2018-100056.
2. Barakat R, Díaz-Blanco A, Franco E, Rollán-Malmierca A, Brik M, Vargas M, et al. Guías clínicas para el ejercicio físico durante el embarazo/Clinical guidelines for physical exercise during pregnancy. Prog Obstet Ginecol 2019;62(5):464-471. DOI: 10.20960/j.pog.00231.