I am very fortunate to not seem to have the need to de-flea my dogs, so therefore do not use flea/tick treatment. However, my girl has just come in season and I intend to mate her this time round. But, I am going to France to a piece of land that we have bought at the end of August and she should have been mated by then. My worry is that she (along with the others) will have to be flea/tick treated to come back. Now, if potentially she is in whelp does anyone know if there would be any detrimental effects to worry about. Of course I will inform the French Vet but I would be grateful if anyone knows if there is a specific treatment that can be used for the Pet passport  for in whelp bitches or whether there isn't anything to worry about.

Frontline states it is safe for pregnant bitches.

The requirements are strict about what products are acceptable. They don't list specific products but rather what chemical they must contain and what parasites they kill.

Googling the chemical and parasite names turns up Drontal for the tapeworm and Advantix or Frontline Combo for the ticks, all of which seem to be okay for use during pregnancy.

(Advantix: "The product may be used during pregnancy and lactation.";
Frontline combo: "The product can be used during pregnancy and lactation";
Drontal: "Consult a veterinary surgeon before treating pregnant animals for roundworms.
The product may be used during lactation.
Do not exceed recommended dose when treating pregnant bitches".)

Thanks for the replies. Very helpful info and puts my mind at rest.