Inclusion Criteria:

A. Criteria for Pregnant Women:

1. Pregnant women in their 1st or 2nd trimester of a singleton pregnancy.
2. Age 18 to 50 years
3. Currently use a smart phone

B. ASD Group at age 18 to 27 months

1. M-CHAT score >= 4 or POSI score >= 3
2. Child has subsequently clinically confirmed diagnosis of ASD, based on ADOS/TAP testing and/or other clinical evaluation

C. Developmental Delay (DD) Group at age 18 to 27-months

1. Developmental screening score on SWYC in the "at risk" range.
2. Child has subsequently clinically confirmed developmental delay on clinical evaluation and/or self-report measure

D. Typically Developing (TD) Group at age 18 to 27 months - None

Exclusion Criteria:

A. Criteria for Pregnant Women:

1. Non-English speaking mother
2. History of severe mental illness in the past year, resulting in inpatient admission

B. All children

1. <35 weeks gestational age at birth
2. History of serious neonatal complications requiring NICU admission for one week or more
3. Known genetic or syndromic condition (e.g. Down Syndrome, etc.) that impacts learning and brain development
4. Hearing impairment

C. ASD Group at age 18 to 27 months

- None

D. Developmental Delay (DD) Group at age 18 to 27 months

1. Screen positive for ASD (M-CHAT >= 4 AND POSI >= 3)
2. First-degree relative who has been diagnosed with ASD

E. Typically Developing (TD) Group at age 18 to 27 months

1. Screen positive for ASD (M-CHAT >= 4 AND POSI >= 3)
2. Developmental screening/assessment score in the "at risk" range.
3. First-degree relative who has been diagnosed with ASD