In recent years, due to the popularity of exercise during pregnancy, the American College of Obstetricians and Gynecologists recommends that pregnant women should engage in 150 minutes of moderate-intensity exercise per week, including aerobic exercise or weight training. This can help reduce pregnancy complications (such as preeclampsia, gestational diabetes, pelvic pain, etc.) and does not increase the risk of miscarriage or premature birth. Pelvic pain during pregnancy is the most troublesome problem for pregnant women, often affecting their daily lives and mental health, leading to the need for long-term use of painkillers and even affecting their daily routine and sleep. Currently, research has also found that exercise during pregnancy can improve pelvic pain during pregnancy and reduce the inconvenience caused by pain in daily life. However, weight training can strengthen spinal stability and reduce lower back pain problems in non-pregnant individuals, but there is currently no research discussing whether weight training for pregnant women can improve pelvic pain during pregnancy, possibly because weight training for pregnant women is not widely accepted by society and is often associated with misconceptions and prejudices. Recent literature synthesis analysis tells us that weight training during pregnancy does not increase the risk of premature birth or miscarriage. Pregnant women in supervised moderate-intensity weight training do not endanger the health of the mother or fetus, and the safety is sufficient. Therefore, we hope to understand the effects and mechanisms of weight training during pregnancy on pelvic pain during pregnancy through this study.

Pregnancy-related pelvic girdle pain is one of the most troubling issues for pregnant women. Everyday activities, such as walking, standing, sitting, and even lying down, can potentially trigger or exacerbate the pain. The diagnostic criteria for pelvic girdle pain are relatively complex. Since the 2008 European guidelines suggested clinical physiotherapy test conditions, they have gradually been adapted for pregnant women. In 2021, Monika revised the diagnostic criteria, allowing pregnant women to self-check for pelvic girdle pain diagnosis, with the following self-test conditions:

Pregnant women have experienced at least one day in the past four weeks when pelvic girdle pain has affected their daily lives.

They can clearly point out the painful area (e.g., sacroiliac joint or pubic symphysis joint pain).

At least one positive anterior pelvic girdle pain test item, or two positive posterior pelvic girdle pain test items, are confirmed through a "pelvic girdle pain self-check." Research has found that 50-70% of pregnant women experience pelvic girdle pain during pregnancy, with 33%-50% experiencing pain even before 20 weeks of gestation. However, 7% continue to have pelvic girdle pain issues for life after childbirth. Pregnancy-related pelvic girdle pain affects daily life and mental health, often leading to long-term use of painkillers and affecting daily routines and sleep.

Recent research suggests that weight training can strengthen spinal stability and reduce lower back pain in non-pregnant individuals. The American College of Obstetricians and Gynecologists recommends pregnant women engage in 150 minutes of moderate-intensity exercise per week, including aerobic exercise or weight training. Studies also show that exercising during pregnancy can improve pelvic girdle pain, reducing inconvenience in daily life, but it cannot reduce the incidence of pain.

In a 2019 survey about pregnancy-related pain, 47% of pregnant women reported having lower back pain during pregnancy. The study found that the fewer times women exercised per week before pregnancy, the more likely they were to experience lower back pain during pregnancy.

However, most current exercise intervention studies for pregnancy-related pelvic girdle pain focus on aerobic exercise rather than weight training. Weight training for pregnant women has not yet been widely accepted, and there are many misconceptions. However, meta-analysis of literature shows that weight training during pregnancy does not increase the risk of preterm birth or miscarriage. Moderate-intensity weight training under guidance does not harm maternal or fetal health, and its safety is sufficient. Therefore, we want to understand whether weight training, as opposed to traditional aerobic exercises, can improve pregnancy-related pelvic girdle pain. Are there differences in muscle cell proliferation and differentiation during pregnancy compared to non-pregnant adults? Does incomplete muscle cell differentiation affect muscle strength, leading to pain in pregnant women? And what mechanisms do weight training exercises use to improve pain?

Inclusion Criteria:

• Pregnant women who are within 14 weeks of gestation and carrying a single fetus.
• Pregnant women who can clearly identify the location of their pelvic girdle pain (e.g. sacroiliac joint or pubic symphysis pain).
• Pregnant women who have at least one positive result in a front pelvic girdle pain test or two positive results in a back pelvic girdle pain test based on the "Self-Administered Pelvic Girdle Pain Test".
• Pregnant women assigned to the intervention group must be able to comply with the exercise program.
• Pregnant women assigned to the control group must not engage in weight training.

Definition of weight training: The use of resistance to induce muscular contraction, with the goal of increasing strength and endurance of the muscles. This can be achieved systematically using weights, such as one's own body weight, or equipment that provides resistance to muscle contraction, such as dumbbells, barbells, or resistance bands.

- Participants will receive follow-up care and delivery at National Taiwan University Hospital in Hsinchu.

Exclusion Criteria:

• For pregnant women with twins or multiple pregnancies

• With any pregnancy exercise contraindications from the American College of Obstetricians and Gynecologists, including:

  • Pre-existing internal medical conditions such as severe unstable heart disease, restrictive lung disease, symptomatic severe anemia, poorly controlled hypertension, poorly controlled diabetes, poorly controlled thyroid disease, and other similar conditions.
  • Pregnancy-related conditions such as early rupture of membranes, signs of preterm labor, incomplete cervix closure, history of cervical cerclage, habitual miscarriage, and previous history of preterm birth.

• History of spinal or pelvic surgery

• Known pelvic pain before pregnancy, such as lumbar or pelvic fractures or chronic pain caused by previous surgery

• Clear diagnosis of pre-pregnancy back pain causes, such as herniated discs or nerve root diseases

• Regular use of pain relief medications before pregnancy, such as acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), morphine, and platelet-rich plasma (PRP) therapy

• Regular weight training habit before enrollment (at least twice a week)

• Not planning to give birth at National Taiwan University Hospital

• Already participating in other interventional clinical trials.

pregnant women