To accommodate Davies, Vicky Owens switches from the flank to No 8.
"Injuries have forced the changes but I've got no hesitation throwing in Dyddgu and Nia," said Wales head coach Rhys Edwards who will be hoping his side can bounce back from the narrow 10-12 defeat to Ireland on Sunday.
"Nia has matured a lot as a player over the last year and she has progressed a lot. She came on against Ireland and had some really nice touches. Dyddgu has come into the squad quite late but I have no qualms about putting her in.
"With Tails (Rachel Taylor) coming back from injury, she played most of the game against Ireland which is more than we originally planned, so we want to ease her back in gently so Gemma Hallett will take over the captaincy."
France are notoriously difficult to beat on their home patch and will be looking to win their first win of the campaign after suffering a shock defeat to Italy last week in Rovato.
"The fact we created so many chances against Ireland was a huge positive and we basically stopped them playing for most of the game, except for about five minutes," added Edwards. "We know we have to be more clinical and ruthless against France who will be smarting from their defeat to Italy.
"Despite the defeat last week we've set out stall out in the way we want to play the game and if we repeat that type of performance I see no reason why we can't come away with a win."
Wales Women v France at Laon, Fri 8th February, KO 6.30pm
15 Dyddgu Hywel (Caernarfon)
14 Caryl James (Cardiff Quins)
13 Elen Evans (Waterloo)
12 Rebecca De Filippo (Cardiff Quins)
11 Philippa Tuttiett (Cardiff Quins)
10 Elinor Snowsill (Bristol)
9 Amy Day (Unattached)
1 Megan York (Blaenau Gwent)
2 Lowri Harries (Neath Athletic)
3 Catrin Edwards (Cardiff Quins)
4 Gemma Hallett (Pontyclun - Capt)
5 Shona Powell Hughes (Neath Athletic)
6 Nia Davies (Cardiff Met)
7 Sioned Harries (Cardiff Quins)
8 Vicky Owens (Pontyclun)
16 Carys Phillips (Cardiff Met)
17 Bethan Howell (Seven Sisters)
18 Jenny Davies (Waterloo)
19 Rachel Taylor (Bristol)
20 Delyth Davies (Cardiff Met)
21 Laura Prosser (Pontyclun)
22 Leila Johns (Unattached)
23 Rafiuke Taylor (Sea View)