Clear answer: No.
There is a persistent legend that a bitch should have gone through pregnancy, birth and puppyhood at least once in her life in order to have a “normal” development and to avoid behavioural problems, but this is… just a legend. This legend has no basis in fact. In particular, it does not prevent later false pregnancies.
Cancer prevention through pregnancy?!
“There is also the belief that giving birth is also useful in preventing cancer in a bitch, which is why it is still recommended from time to time to have a bitch mated at least once, even by some vets. Here, too, it should be noted that there is no scientific evidence that bitches that have never had a litter are more likely to develop cancer or even die than bitches that have had puppies once or several times.”
Source: Ein Mal im Hundeleben Welpen haben [your dog, Dog Magazine from Austria]