I can yoink some quotes from 3.5 sources. I know Rich takes his inspiration from much earlier sources, but the later editions crib plenty from their predecessors so it might not be too different.
From Drow of the Underdark:
The drow are notably more fertile than are their surface-dwelling
cousins. They become pregnant more easily and have a
slightly shorter gestation period.
The drow do not believe in using magic or anything more
than basic herbal medicines to aid a mother through the pain
and danger of childbirth. Should she die in the process, she is
clearly too weak to contribute further to the race anyway.
Once drow children are born, they are raised by servants
(drow parents rarely spend much time with their offspring) in
communal living areas used by families or even entire houses.
Drow children are no less temperamental than drow adults, and
are in fact encouraged to resolve their difficulties through violence.
If a child is not strong enough to survive and thrive in this
environment, well, better that it not live to an equally violent
adulthood. Perhaps spurred on by these hostile circumstances,
drow children develop much faster than other elves—almost as
swiftly as humans, in fact—often beginning schooling as early
as age eight or ten.
Drow schooling is heavily focused. Although the children
receive a sufficient grounding in all the basics of learning, they
are trained primarily in the drow faith, as well as in one or two
other areas for which they show both an aptitude and an interest.
Once they have reached adolescence (at about age 20, by
which time over a third of them have been murdered or sacrificed),
their training shifts from a group endeavor to apprenticeship
with a single mentor. Assuming their mentor doesn’t
slay them for some minor infraction, they eventually become
skilled enough to adopt their trade on their own—which often
involves competing with other apprentices to take the mentor’s
place when she dies.
And both these about non-Drow Elves are taken from Races of the Wild:
ELVES AND ADULTHOOD
Table 6–4 of the Player’s Handbook suggests that elves don’t
reach their full physical growth until an age of 110, at a minimum.
That’s not entirely accurate. The random starting age for
elves is simply the age at which many elf adventurers feel ready
to leave their forests and roam the world outside for a time. More
than a few elves have commenced their adventuring careers at
much younger ages.
Elf children grow almost as swiftly as human children to age
15 or so; a 10-year-old elf boy and a 10-year-old human boy are
nearly the same size and have similar mental and emotional
maturity. The elf will be shorter and slighter than his human
playmate. He is also quite likely to be more patient, observant,
and self-sufficient, simply due to the influence of growing up in
an elf household.
Humans finish their “filling out” and full adult growth by
about age 20, but elves take a little longer, rarely reaching their
full height and weight before age 25. After that, elves remain
virtually timeless, decade after decade. Not even another elf
can tell at a glance whether an elf is 25, 50, or 100 years of
age. A few minutes’ conversation quickly dispels the mystery,
of course; elves gain experience, grace, emotional maturity,
patience, and wisdom throughout these ageless decades. Even
so, some elves are remarkably poised for their age, and some
elven romances tell the tale of a grieving elf of 150 years of age
discovering life and joy again in new lover of only 25 or 30 who
carries himself or herself like an elf of 100.
Though an elf reaches mental and physical maturity at the
age of 25, very few elves become parents until much later in
life. Elves rarely feel that they’re ready to settle down and
begin families before they’re at least 100 years old, and most
stop having children soon after reaching the age of 200. Elf
children are not as numerous as one might expect, given the
length of an elf’s child-rearing years, because elves are less
fertile than humans and other shorter-lived races. A typical
human couple might have one to four children over the
course of a decade, but an elf couple might take fifty years
to have the same number of children.
Elves have a gestation period of approximately nine months,
just as humans and other similarly sized creatures do. Once a
child is born, his or her parents usually raise the youngster for
the first few years, and then foster him or her out to a succession
of older relatives until he or she reaches maturity. This
practice provides training for the child in a variety of areas
and allows the parents to return to the pursuit of their own
interests. It also encourages young elves to develop their
own sense of self and a degree of personal independence.
And a friend of mine often quotes from a Drow focused Dragon Magazine. Which apparently details that Lolth had altered Drow biology increasing their fertility and maturation rate substantially. It went on to say that most Drow pregnancies are twins, but usually one of the babies kills the other in the womb, and when this 'fight' happens the expecting mother is ecstatic. Personally I think that was a jump the shark moment, the writer getting carried away with 'look at how evil they are', and I'm glad the reference didn't endure into DotU.