Sort of. The applicable regulations specifically excludes IVF as an insured service except for one narrow circumstance.
Some background:
OHIP decides whether you are eligible for OHIP and whether the Plan
covers the health services you are claiming.
You should review the reasons that OHIP gives for its decision,
including the relevant sections of the Health Insurance Act. If you
think that OHIP’s decision is wrong, you may appeal the decision to
the Health Services Appeal and Review Board.
Fortunately, the decisions of the Health Services Appeal and Review Board are online.
This decision from 2003 (and also this other decision from 2013) says:
Section 24 of Regulation 552 provides for exclusions to s.11.2 and
subparagraph 23 specifically excludes IVF as an insured service
except for the narrow circumstance specified therein:
24 The following services rendered by physicians or practitioners
are not insured services and are not part of insured services …:
(23) In vitro fertilization other than the first three treatment
cycles of in vitro fertilization that are intended to address
infertility due to complete bilateral anatomical fallopian tube
blockage that did not result from sterilization.
As to why and how these regulations came about, someone helpfully wrote a thesis which touches on the subject (this quote starts on page 124 -- there's more there than will comfortably fit in a block quote, but I urge interested parties to give it a read)
In Ontario, in vitro fertilization was fully covered by OHIP from 1985
to 1994 as long as the treatment was performed in a hospital setting
rather than in a private clinic.
[...]
In the early 1990s, Ontario faced pressure from intense economic
restructuring and a turbulent political climate. In December 1993, the
New Democratic Party (NDP) government adopted the Expenditure Control
Plan (Bill 50) that led to much discussion in all major ministries
about reduction in public spending. The Health Ministry decided
accordingly to amend the Health Insurance Act to delist medically
unnecessary procedures. The province thus decided to limit its
funding and to cover IVF exclusively for women with blockage of both
fallopian tubes, a diagnosis which represents only 1% of the cases of
infertility.
[...]
However, Ruth Grier, Minister of Health, was more cautious regarding
the technology. She argued that Ontario was the only province to fund
and that the consensus around assisted reproductive technologies was
to proceed with care.
To summarize: Ontario does not fund fertility treatments except in an extraordinarily narrow set of circumstances.