TT #3 · Parshas Tazria · Aliyah 1 · Passuk 2
English: Speak to the Israelite people thus: When a woman at childbirth bears a male, she shall be impure seven days; she shall be impure as at the time of her condition of menstrual separation.
Chabad.org — Chumash, English translation + Rashi for Vayikra 12:2
Torah Temimah cites Niddah 27b.
English: “If a woman conceives and gives birth to a male” teaches that even if she gives birth only to something resembling what she had emitted as seed, she has the impurity of childbirth.
Textual inference
The phrase “if a woman conceives” supplies a basis for including a birth in which the product has become seed-like.