No, it is not a good idea to do a liver flush at any time during pregnancy.
Cleansing of any kind during pregnancy, should be undertaken very carefully, and under direct supervision of your doctor or midwife.
The Ortho Phos contains Orthophosphoric Acid F.C.C. this is not safe to use during pregnancy or while nursing.
Below is a list of herbs to avoid during pregnancy, check your supplements carefully.
HERBS NOT TO BE USED AT ALL:
Angelica Penny Royal
Cinchona Poke Root
Eucalyptus Oil Rue
Juniper Shepherds Purse
Lovage Tansy
Ma Haung or Brigham Tea (ephedra)
Male Fern Wild Ginger
Mistletoe Wormwood
Mugwort Yarrow
These herbs should only be used in combinations under direct supervision, sparingly, only in the last 6 wks of pregnancy.
Black Cohosh, False Unicorn, Golden Seal
These herbs have laxative properties and should only be used under supervision, in combinations and in sparing amounts.
Aloe Vera Mandrake
Barberry Rhubarb
Buckthorn Senna
Cascara Sagrada
If I can be of any additional help please let me know.