Progesterone cream during the first trimester of pregnancy

Patient: HI. I am 40 years old and have been trying to conceive for 6 months.3 months ago I started taking B6 50mg daily to increase my luteal phase which was 10days. Then I took a Saliva test for hormone through ZRT laboratory and my progesterone and estradiol were both on the lower side(progesterone:95pg per ml estradiol:1.4pg per ml). Lately I started a progesterone cream after ovulation and got pregnant that last cycle. My question is: should I continue using the progesterone cream during the 1st trimester? is it safe to use it during pregnancy?so far I am still applying it(Iam 4 weeks pregnant), will it cause any harm to the fetus?I strongly believe that this cream helped me conceive and I am scared of stopping it because a drop in progesterone could lead to a miscarriage. Please advice.Thanks

Doctor: