Good question. Certain elements of venom almost certainly are able to cross the placenta. I am not certain what specific proteins are capable of doing this, though I believe they would have to be small. Passive and active transport.   

 Large molecules (possibly intact proteins) can cross the placenta via pinocytosis. The mechanism involves immunoglobulin-binding protiens so the transfer is fairly specific. There are proteins in some snake's venom that can bind with immunoglobulin-G such as the one reported in this paper http://www.jbc.org/content/280/34/29989.full, which could make it possible to get transported across the placenta. Experiments would need to be done in primates or rodents since many other animals do not have the immunoglobulin transport mechanism.

if some parts of the venom crosses... can it be neutralized by giving specific Anti-snake Venom, as those proteins are specified to that venom??

Some venom components like L-amino acid oxidase (LAAO), which exists in most snake venom, is suspected to bind to immunoglobulin (Ig) but antivenins molecular function may not block the Ig binding site and may not cross the placenta unless bound to the target. This would make the antivenin non functional for LAAO that had crossed to the fetus before administration of the antivenin. The results for the fetus will really depend on the dose and timing. Have you seen this paper? http://www.wemjournal.org/article/S1080-6032(09)00026-X/pdf Some excellent references too.

The answer is yes and no. In one case of secundagravida, we found that the mother was bitten by an Echis Carinatus and had developed hemotoxicity, including de-fibrinogenation, hematuria etc. She was advised C-section after the antisnake venom administration and BT/CT improvement. Upon PP, the fetus was having normal coagulation properties. It may be due to the administered doses.

In another case, the mother was brought late and had developed severe coagulation defects. There was almost no movement in fetus and no fetal heart rate. The venom might have been responsible for the casualty.

In all such cases, proper antivenin has to be administered and the mother should be advised for Cesarean, if normal deelivery does not look possible. There is no need to take samples from the baby.

Thank you Ranjan sir,

In your first case scenario whether fetus had features of snake envenomation before the C-section and does any features of placental insufficiency/ abruptio placenta was present

we had  a case of snake bite(hemotoxic)in which we had only blood stained aminotic fluid. 

If the fetal findings of nil movement and no heart rate may be due to complications in mother following the Echis cranitus snake bite... then fetus is not directly affected by snake venom. at this stage does C- section help in saving the baby.

No, in first case, it was full time and the baby was well developed. No sign of hemotoxicity found (we were surprised, but god is great)...

In the second case, hypotension was observed in the mother alongwith sever coagulation defects. Amniotic fluid was also affected.

In order to save the baby from possible transmission of venom components, C-section is advised under extreme care, as you know Coagulation defects are already there so loss of blood may be more... 

It is possible to see developmental effects in the fetus that are a result of maternal physiological effects without any transfer of venom components across the placenta. Placental abruption, for instance, can be a result of maternal blood disorders, high blood pressure, etc...

Dear Ron, the mother was severe hypotensive. There could have been possibility of short period hypertension under anxiety and later hemotoxic hypotension. 

Also, I went through the paper you mentioned. It is indeed very unscientific to place all types of ophitoxicity together. Have you seen any paper talking about Malaria, Typhoid and Viral fever together? Hemotoxicity and neurotoxicity should be dealt separately and reported separately as their prophylaxes would be entirely different. Also there was a category of unknown bites with significantly high number, which makes the study questionable. So, for all the researchers, it is requested that the species and the antivenin dose should be compulsorily reported for better assessment at reader's end...