This study's aims are to examine the effects of yoga and aromatherapy on women's stress and immune function during pregnancy.

This longitudinal, prospective, randomized controlled trial recruited 75 healthy pregnant women from a prenatal clinic in Taipei using convenience sampling. The participants were randomly assigned to the aromatherapy group (n=25), yoga group (n=25) or control (n=25) group using Clinstat block randomization.

The aromatherapy group received 70 minutes of aromatherapy massage once biweekly for 20 weeks; the yoga group participated in two weekly 70-minute yoga sessions led by a midwife certified as a yoga instructor for 20 weeks; the control group received only routine prenatal care. All participants' salivary cortisol and immunoglobulin A levels were collected before and after yoga or aromatherapy every 4 weeks from 16 to 36 weeks' gestation.

To collect a sufficient quantity of saliva, we used Salivette® cotton swabs (Salimetrics, State College, PA, USA), which were stored in double-layer plastic tubes with a lid. When participants chew a swab for about 2 to 3 minutes, saliva flow is stimulated to a sufficient amount (1 mL) for collection. After the tube was centrifuged at 1000 x g for 2 minutes, saliva was stored at -80°C until assay for salivary cortisol and IgA concentrations.

Cortisol was measured using a competitive enzyme-linked immunoassay (ELISA) kit (Cayman Chemical Company, USA), and salivary IgA was measured using double-antibody sandwich ELISA method per the manufacturer's instruction (ICL, Inc., USA).

Inclusion Criteria:

• Normal pregnancy
• Age 20-45 years
• Agreed to follow-up collections of saliva samples
• Could read and write Chinese

Exclusion Criteria:

• Oral steroid use
• History of severe illness (e.g., heart disease, systemic lupus erythaematosus, metabolic disorders) or depression.
• Drug use (prescribed or illicit).
• High-risk pregnancy (i.e., first-trimester vaginal bleeding, artificially insemination, multiple gestations, foetal growth restriction or other abnormalities).