O-Negative Blood Type Inheritance: What Parents with O- Blood Should Know

When both parents have O-negative (O-) blood, all of their biological children will also have O- blood. This is because the O allele is recessive; a person must inherit two O alleles (one from each parent) to express the O blood type. Since both parents can only pass on an O allele, every child receives two O alleles.

Key Facts About O-Negative Blood

• Prevalence: O is the most common blood type worldwide, found in about 45% of the population.
• Universal Donor: O- red blood cells can be transfused to patients of any blood type, making O- donors critical in emergencies.
• Rh Factor: The negative sign indicates the absence of the Rh(D) antigen. An O- parent cannot pass on a positive Rh factor.

While blood type inheritance is predictable, other genetic traits follow more complex patterns. If you have questions about genetic risks, consider speaking with a genetic counselor.