AIM: Explore the complexity that arises with respect to our understanding of the word mother(hood) in non-genetic gestational (full) surrogacy. METHODOLOGY: • Consider the recent achievements of reproductive biology • Analysis of the word mother(hood) and what is “natural” mother(hood) • Consider the influence of the gestational mother (being-in-the-womb + genotype-phenotype distinction) • Consider the “supplementarity” of the gestational mother. CONCLUSION: Both genetic mother and gestational mother are of equal importance for the child’s existence. KEY CONCEPTS: • Being-in-the-world • Thrownness • Genotype-Phenotype distinction • Supplement