This has been bothering me after watching episode 1 again... why didn't the Doctor know she was now a woman? I've googled this and there doesn't seem to be any reference to this answer. After having been a man for 12 (13 including War Doctor) incarnations, wouldn't you know that you don't have male parts or even that you now have something hanging off your chest? (cos I'm sure that 12 wasn't wearing a bra) Wouldn't this indicate some sort of change, different to previous regenerations?

...and yes, I know the Doctor is an alien and therefore he/she may be different to humans, but to my understanding of Doctor Who (correct me if I'm wrong) - the only difference physically between humans and Time Lords is that they have two hearts.

It just seemed weird that when Yaz said "you're a woman" on the train, the Doctor seemed shocked/surprised but physically the Doctor would've realised that something was different after the regeneration. This is especially reinforced when the Doctor says something like she was an old man before.

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    As you might have seen, the Doctor does not always notice things super-quickly. I can’t remember his mind ever being particularly focused on his penis. Now, if the regeneration had resulted in something really weird, like new teeth, maybe she would have spotted it quicker. Dec 6, 2018 at 9:01
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    I'd say the considering she fell out of the TARDIS and crashed into a train almost immediately after regenerating, she didn't have much time to think about her private parts until the scene you mentioned.
    – ElibE876
    Dec 6, 2018 at 9:11
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    "the only difference physically between humans and Time Lords is that they have two hearts." - Actually, there's also the Doctor's "respiratory bypass system", which was mentioned quite a few times in Old Who - I think the 3rd and 4th Doctors in particular used it to breathe when a monster was trying to strangle them. Some of the novels introduced the "lindal gland", which emits a hormone necessary for the regenerative process. The episode "Extremis" mentioned Time Lords having three brain stems, and the "Blood Heat" novel had the 3rd Doctor claim to have a lower body temperature than a human.
    – AJM
    Dec 6, 2018 at 14:01
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    I remember him noticing that he had new kidneys after a regeneration, therefore wouldn't she know that she is missing something... that is "something really weird."
    – Pikachun
    Dec 7, 2018 at 6:17

1 Answer 1


The post-regenerative period is always saddled with various mental issues. This can include memory loss or confusion, a tendency to think or respond in the manner of past regenerations, and in some cases, violent behavior.

Quite often The Doctor will appear perfectly fine in the moments after regeneration (Five sitting up, apparently fine, Ten carrying on with the same conversation with Rose) but will fall into a stupor shortly after.

In the case of the new Doctor, she was clear-minded long enough to look at herself in the mirror and be pleased with the results, but having fallen out of the TARDIS almost immediately after, and then through the top of a moving train, being a little bit confused about the details of the past few minutes would be perfectly understandable.

  • this is a good answer... even though the episode didn't really make sense in regards to falling on to a train, after all a person normally checks themselves out to make sure they are ok but the Doctor went from falling to talking without checking herself out... if she did then she would've noticed that she is a woman now.
    – Pikachun
    Dec 7, 2018 at 6:21
  • @Pikachun "a person normally checks themselves out to make sure they are ok" 1. The Doctor rarely does what anyone would normally do, and 2. a few regenerations ago (11th/Matt Smith) he spent time checking out his new body first, only to discover that he was in the middle of crashing the TARDIS. It's possible that after regenerating into the 13th, the Doctor decided that based on that experience, evaluating her surroundings should take priority over examining her new body. Mar 2, 2020 at 15:28

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