In the 6th week of pregnancy, hCG levels can vary widely among women. A hCG level of 635 is generally within the normal range for this stage. However, it's important to note that individual levels can differ and what matters most is how they rise over time. Your doctor will monitor your hCG levels through blood tests to ensure they are increasing appropriately. If you have any concerns or experience symptoms such as severe pain or bleeding, it's best to consult with your healthcare provider for further evaluation and guidance.