I have to disagree. I would much rather have a Sprite Zero than a regular Sprite. Artificial sweeteners have literally been shown to cause no, zero, zilch, nada side effects and are regarded as safe for consumption in pregnant and non-pregnant women.
Excess sugar consumption, on the other hand, has been linked to ill effects in pregnancy.
As for me, I would pick the diet sprite/sprite zero every time (up to about 2 per day).
On these kinds of issues it is good to do real research vs. listening to people who say things like "splenda is poison," without referencing any peer-reviewed study or journal article. There have been around 100 studies showing Splenda is safe for human consumption in amounts way exceeding "moderate" levels. On the other hand, there have been no scientific studies showing that it is dangerous....