Marvel Codification (Pregnancies are the key)

[Slimybug]

So I'm a big nerd about codifying the MArvel timeline. I've been told ad nauseum that it is a fruitless cause, but I still enjoy it. People say Franklin Richards' growth has a lot of contradictions in it, but I haven't seen that yet. From what I understand, they've finally started to age him up a little, so he's likfe 14 now.

What I ultimately realized is that a lot of the codification depends on two things: Peter's high school and college years, and Kitty Pryde's introduction, which conveniently occurred right after Peter's college graduation.

Peter's Schooling
1962, Aug. Peter Parker was 15 when he becomes Spider-Man. (Amazing Fantasy #15).
1965, Sept. Peter Parker graduates high school (ASM #28). So those three years, from 62 to 65, were real time! He then, in real time, begins attending college 3 issues later, in #31.
1967, Nov. Sue becomes pregnant (FF Annual #5)
1968, Nov. Franklin Richards is born (FF Annual #6). So the past year took place in 9 months
1978, Oct. Peter Parker graduates college. (ASM #185) So the past 13 years take place in 4 years, including the one year that was just 9 months!

Kitty's age
1979, Oct. Kitty Pryde is 13 when first introduced. (UXM #129)
1983, Feb. Kitty turns 14. The last 2 years took place in under a year (Special Edition X-Men #1)
1990, Aug. Kitty has her 15th birthday. The last 7 years were 1 year. (Excalibur #26)
1996 Kitty has implicitly had sex with Pete Wisdom, so let's hope she's 18. Meaning the last 6 years were 3 years.
2004, Jul. Kitty returns to the Xavier Institute as an adult (Astonishing X-Men #1) AT least 5 years have passed, meaning at least 12 years have passed since Peter was bitten.

I'd actually think there has to be at least 10 years since Kitty was introduced, so there has to be at least 17 years of Peter being Spider-Man.

These are all attempts at codification that have been pointed out to me in another thread, but they all are really flawed and thus should be ignored.
1968, Dec. Daredevil entertains troops in Vietnam
2014, Jun. Peter stated to have been bitten 13 years ago
2019, Jun.Peter stated to be in his mid-20s - This one is particularly ludicrous
2019, Sept. X-Men stated to have been going on for 10 years (Powers of X #1)
2021, Jun. Flashback to Daredevil entertaining troops "12 years ago” (The Marvels #1)

A later revelation then came to me: Pregnancies are the key! If we count up the amount of normal 9-month pregnancies that were carried to term, that should give us some indication of the amount of time that would have had to have passed. The problem is, it's a challenge to track down when all these pregnancies were first stated, and when all the births happened, so I'd appreciate any help in that.
As it stands, excluding Invisible Woman's first pregnancy, and Gwen Stacey's which both happened in Peter's college years, we still have 13 pregnancies left, which, excluding overlap, would take up 9.75 years of real time!

Pregnancies
Crystal (gives birth in Mar. 1982 - Fantastic Four #240)
Madelyne Pryor - Dec. 1985-Jan. 1986 (X-Men/Alpha Flight #1-Uncanny X-Men #201)
Medusa (gives birth Dec. 1988 - Marvel Graphic Novel #39)
Dazzler (gives birth Jan. 1991 - New Mutants #99)
Mary Jane - Jan. 1995 - Dec. 1996 (Spectacular Spider-Man #220-Amazing Spider-Man #418)
Jessica Jones (Jan. 2004 [three months along]-Jan. 2006) (Alias #28-The Pulse #12)
Spider-Woman (gives birth in Apr. 2016 - Spider-Woman v6 #4)
Invisible Woman (2nd)
Angel Salvadore
Siryn
Wolfsbane
Lily Hollister
Wasp

Plus these ones that I'm not sure technically had to last 9 months:
Scarlet Witch
Thundra
Ceira / Scar
Quasar