Wikipedia defines antinatalism as follows:
Antinatalism, or anti-natalism, is a philosophical position and social
movement that assigns a negative value to birth. Antinatalists argue
that humans should abstain from procreation because it is morally bad
(some also recognize the procreation of other sentient beings as
morally bad).
In respect to Noble People, Buddhism may possibly appear antinatalist, when it says:
Monks, there are these two searches: ignoble search & noble search.
And what is ignoble search? There is the case where a person, being
subject himself to birth, seeks [happiness in] what is likewise
subject to birth. Being subject himself to aging... illness...
death... sorrow... defilement, he seeks [happiness in] what is
likewise subject to illness... death... sorrow... defilement.
And what may be said to be subject to birth? Spouses & children are
subject to birth. Men & women slaves... goats & sheep... fowl &
pigs... elephants, cattle, horses, & mares... gold & silver are
subject to birth. Subject to birth are these acquisitions, and one who
is tied to them, infatuated with them, who has totally fallen for
them, being subject to birth, seeks what is likewise subject to birth
MN 26
However, for laypeople, Buddhism appears not antinatalist. It says:
To support one's father and mother; to cherish one's wife and
children, and to be engaged in peaceful occupations — this is the
highest blessing.
Maha-mangala Sutta
Buddhism says the pleasant feelings from renunciation, meditation & enlightenment are superior to the pleasant feelings from the household family life. Refer to the Sukhavagga in AN 2.
There are, mendicants, these two kinds of happiness. What two? The
happiness of laypeople and the happiness of renunciates. These are the
two kinds of happiness. The better of these two kinds of happiness is
the happiness of renunciates.
There are, mendicants, these two kinds of happiness. What two? Sensual
happiness and the happiness of renunciation. These are the two kinds
of happiness. The better of these two kinds of happiness is the
happiness of renunciation.
There are, mendicants, these two kinds of happiness. What two? The
happiness of attachments, and the happiness of no attachments. These
are the two kinds of happiness. The better of these two kinds of
happiness is the happiness of no attachments.
It follows it appears Buddhism is not 'antinatalist' because it appears to never say having children is "morally bad". Buddhism appears to merely say (for those capable of entering the Noble Path) not having children brings more happiness when compared to having children.
In conclusion, my personal view is Buddhism is not antinatalist.