The goal of this clinical trial is to learn if maternal left-lateral positioning in pregnancy works to treat fetal growth restriction. This study will also help us learn about the effects of left-lateral positioning on maternal metabolomics, maternal mental health, fetal cardiac function, and delivery outcomes. The main questions it aims to answer are:

• Does maternal left-lateral position in a pregnancy with fetal growth restriction improve the baby's growth?
• How are maternal metabolomics, delivery outcomes, maternal mental health, and fetal cardiac function impacted by maternal left-lateral position? Researchers will compare the intervention group to pregnancies with fetal growth restriction that receive standard of care (without left-lateral positioning) to see if left-lateral position improves fetal biometry in fetal growth restriction.

Participants will:

• Practice left-lateral position every day for 4 hours (cumulatively) with 10-mins stretching after every hour of left-lateral position, or continue to receive standard of care
• Visit the clinic once after 4 weeks for a follow-up research visit, and at the time of delivery

Tracking of the physical activity and adherence to left-lateral position at home in intervention group A will be done through a fitbit (smart watch) given during enrollment. A fitbit will also be given to participants in intervention group B, receiving standard of care, to monitor their physical activity trends at home.

Inclusion Criteria:

• Pregnant persons between 18 - 65 years of age, with a diagnosis of fetal growth restriction, with an estimated fetal weight less than tenth percentile
• Participants with a singleton pregnancy between 24- and 34-weeks' gestational age
• Participants with fluency in English or Spanish language

Exclusion Criteria:

• Patients with a known history of deep vein thrombosis, pulmonary embolism, or hypercoagulability disorder
• Patients with a pre-pregnancy BMI greater than 40
• Pregnancy with severe abnormality in umbilical artery Doppler flow, including absent end-diastolic flow (AEDF) and reverse end-diastolic flow (REDF)
• Patients receiving anticoagulation therapy
• Pregnancy with suspected chromosomal anomalies or a multifetal pregnancy
• Patients with an active smoking status during pregnancy

The sonographer doing the fetal biometry at enrollment and during the 4-week follow-up visit will be masked to the study group assigned to the participant.