IVF is certainly time intensive. During the various stages of your cycle, you will need to check into your fertility clinic many times a week. Your appointments will not all be planned in advance, and your doctor may inform you that your presence is required at less than 24 hours notice. This is particularly true in the monitoring phase of the cycle, and retrieval and transfer day could both take place during any of three or four days, without knowing in advance.
Unless your job has a high degree of flexibility, IVF will mean that you will need to take a lot of time off work and being granted annual leave may be hard. Informing your boss and coworkers that the reason for your frequent absences is the fact that you are trying to get pregnant may well make getting time off more easy. Your boss will have more understanding for your need to get time off if he or she knows why you need it.
At the same time, everybody at work knowing about your IVF adventure can make it harder to focus on your job, and you will certainly get many comments. No matter how supportive they are (and often, they are not!), it can be very hard to have people sticking their noses into one of the most private things you will ever do. And what if you have been through several unsuccessful IVF cycles, only to be passed up for that promotion because everyone knows you are hoping to be a parent in the near future?
These decisions are certainly tough. Ultimately, only you can decide whether you are better off being open about having IVF or not. Your trade union or a lawyer can be of help if you are trying to work out whether you can take medical leave or need to take holiday time.