This film was cut by the US MPAA before general theatrical release to gain a US R rating. It was cut further for its Australian release.
The uncut R1 disc runs to 92:18 NTSC, which calculates out to roughly 88:37 PAL, compared to 87:49 PAL for this new R4 DVD. There is an MGM lion logo and some dead time before the start of the feature running to about 13 secs, and one brief MGM lion logo (one roar) at the end running to about five seconds.
Hence there is a difference of 48 secs between the two DVDs. The French disc, titled Chromosome 3, runs to 87:44 PAL and has no MGM logos at the start or end. The 'birthing' scene on the Dendy French disc is missing one crucial moment, among others: the second foetus licking shot. The first one is shown head-on, while the second is more of a close-up with the camera on Samantha Eggar's left. IMDB reports that all of the European PAL DVDs are cut. Unfortunately, this new Region 4 PAL release by MGM is also similarly cut.
As mentioned above, the old Australian VHS rental is missing even more footage than the censored US R version. The only uncut version available on DVD is still the current R1 MGM unrated release.