According to a 2021 study, it is recommended that the vitamin D level in our blood be above 25(OH)D. The research states ur levels need to be closer to 50 nmol/L (20 ng/mL). McBurney MI, Blumberg JB, Costello RB, Eggersdorfer M, Erdman JW Jr, Harris WS, Johnson EJ, Hazels Mitmesser S, Post RC, Rai D, Schurgers LJ. Beyond Nutrient Deficiency-Opportunities to Improve Nutritional Status and Promote Health Modernizing DRIs and Supplementation Recommendations. Nutrients. 2021 May 28;13(6):1844. doi: 10.3390/nu13061844. PMID: 34071268; PMCID: PMC8229216.
If you are taking a vitamin D supplement which is recommended by NHS UK for pregnant women, three tablets at 25 UG may be enough to bring your vitamin D levels into the optimal range. Talk to your doctor to ensure that you are taking in enough vitamin D.
If you would like to read the study, here is the link.