Clinicians have been assessing the effectiveness of bed rest in hospital or at home to improve pregnancy outcomes for women with a multiple pregnancy.

Bed rest at home or in hospital is a very common intervention to prevent preterm birth in women with multiples. 
Strict bed rest refers to the confinement to rest in bed the entire day and to minimise all physical activity, except for toileting and healthcare-related visits. 
Women who are recommended to partial rest are allowed some physical activity, but are encouraged to continuously rest in bed for several hours during the day.

Bed rest, with or without hospitalisation, may have the potential to reduce the risk of preterm birth, fetal and neonatal mortality, and long-term morbidity.

The effectiveness of bed rest for multiple pregnancies is constantly being reviewed in order to better guide doctors in their decisions.

A review in 2001, which was updated in 2010 and 2016, found that routine hospitalisation and bed rest for women with a multiple pregnancy did not reduce the risk of preterm birth, low birthweight, and perinatal mortality. Strict bed rest was associated with going into labour naturally and having babies with a higher mean birthweight. Partial (but not strict) bed rest reduced the rate of high blood pressure.

Currently there is not strong evidence in support of or against bed rest for women with a multiple pregnancy. The best thing to do is speak to your doctor if you have questions or concerns.

Clinicians systemically evaluate the latest evidence of bed rest. 

You can read more about their research at the Cochrane Library.