Unforgiveable/Unforgetable Past Abortion and Miscarriage
From the sutta quote below, you can see that a person's actions while they were alive determines their outcome, and not rituals performed after death.
Also, please watch this video talk and this video talk on superstition by Ven. Ajahn Brahm. In SN 7, you can find many cases where the Buddha criticized superstitions.
In DN 2, we find that astrology, palmistry, divination, tea leaf reading, magic, geomancy, dream interpretation, making predictions etc. are considered &quot;animal arts&quot; and wrong livelihood for monks.
From SN 42.6:

Then Asibandhaka’s son the chief went up to the Buddha, bowed, sat
down to one side, and said to him:
“Sir, there are western brahmins draped with moss who carry pitchers,
immerse themselves in water, and serve the sacred flame. When someone
has passed away, they truly lift them up, raise them up, and guide
them along to heaven. But what about the Blessed One, the perfected
one, the fully awakened Buddha: is he able to ensure that the whole
world will be reborn in a good place, a heavenly realm when their body
breaks up, after death?”
&quot;Well then, chief, I’ll ask you about this in return,
and you can answer as you like.
What do you think, chief? Take a person who doesn’t kill living
creatures, steal, or commit sexual misconduct. They don’t use speech
that’s false, divisive, harsh, or nonsensical. And they’re contented,
kind-hearted, and have right view. And a large crowd comes together to
offer up prayers and praise, circumambulating them with joined palms
and saying: ‘When this person’s body breaks up, after death, may they
be reborn in a place of loss, a bad place, the underworld, hell!’ What
do you think, chief? Would that person be reborn in hell because of
their prayers?”
“No, sir.”
“Chief, suppose a person were to sink a pot of ghee or oil into a deep
lake and break it open. Its shards and chips would sink down, while
the ghee or oil in it would rise up. And a large crowd was to come
together to offer up prayers and praise, circumambulating it with
joined palms and saying: ‘Sink, good ghee or oil! Descend, good ghee
or oil! Go down, good ghee or oil!” What do you think, chief? Would
that ghee or oil sink and descend because of their prayers?”
“No, sir.”
“In the same way, take a person who doesn’t kill living creatures,
steal, or commit sexual misconduct. They don’t use speech that’s
false, divisive, harsh, or nonsensical. And they’re contented,
kind-hearted, and have right view. Even though a large crowd comes
together to offer up prayers and praise … when their body breaks up,
after death, they’re reborn in a good place, a heavenly realm.”
When he said this, Asibandhaka’s son the chief said to the Buddha,
“Excellent, sir! … From this day forth, may the Buddha remember me as
a lay follower who has gone for refuge for life.”