The purpose of this research is to collect blood samples and data from pregnant women who are Rh negative. The blood will be used for the future research and the development of non-invasive prenatal tests to identify Rh blood type status of the baby during pregnancy.

This is a prospective multi-center blood collection study. Women 18 years of age or older with a viable singleton pregnancy between12 weeks and 28 weeks gestation will be enrolled.

Whole blood samples will be collected from each enrolled patient. Maternal specimens will be processed to plasma and stored for future testing with non-invasive prenatal tests to identify fetal Rh status.

Baby RhD blood type status will be recorded after delivery. All obstetric clinical management will take place per standard clinic practices and procedures and will not be altered by participation in the study.

Inclusion Criteria:

1. Willing and able to provide written informed consent
2. 18 years of age or older at enrollment
3. Women with a viable pregnancy (with documented fetal heartbeat) between 12 weeks, 0 days and 28 weeks, 0 days gestational age
4. Women with RhD negative antigen status by serology
5. Willing to provide neonatal ABO and RhD genotyping status

Exclusion Criteria:

1. Women with multiple gestation pregnancy

Pregnant women who are RhD negative and between 12 and 28 weeks gestation.

We do not plan to share individual participant data with other researchers. Any shared data will be de-identified data at the cohort level in aggregate.