The posters were put up in two locations in January
An advertising watchdog has found a billboard campaign on abortion was not misleading.
A poster by the pro-life campaign group, Both Lives Matter, appeared in two locations in Northern Ireland in January.
The poster featured the claim "100,000 people are alive today because of our laws on abortion. why change that?".
The British Advertising Standards Authority (ASA) says it received 14 complainants, challenging whether the claim was misleading and could be substantiated.
The Both Lives Matter group said they had attempted to estimate the number of people alive in Northern Ireland today because the 1967 Abortion Act introduced in Great Britain had not been introduced in Northern Ireland.
They said it was not possible to calculate an exact figure, but 100,000 represented a credible and conservative estimate.
They provided a link to a report they had published on their website, and also provided a second methodology based on the application of the abortion ratio in Scotland to Northern Ireland.
In its ruling, the ASA said it considered that readers were likely to understand the claim to relate to the number of individuals alive today that were born to mothers who would have aborted their pregnancy if it had been legal to do so.
It also noted the views of many of the complainants that the claim was presented as an absolute, objective claim and therefore would be understood by readers of the ad to be a precise figure rather than an estimate.
The ASA said: "However, we considered that 100,000 was a large, round number that readers would typically associate with estimates.
"Furthermore, readers would appreciate that it was not possible to calculate the precise number of abortions that would have theoretically occurred in Northern Ireland if abortion had been legal over the past 50 years.
"Accordingly, we considered that readers would expect the claim to be an estimate based on a methodology that showed there was a reasonable probability that around 100,000 individuals were alive today who had been born to mothers who would have aborted their pregnancy if it had been legal to do so."
Dawn McAvoy from Both Lives Matter says they put together a robust report.
"We had gathered information from government statistics, health statistics looking at abortion rates in England and Wales and Scotland - which is separate - and Northern Ireland figures for women from Northern Ireland who (have) gone over to Great Britain and had abortions".