Maternity leave

My baby is 9 months and I’m going back to work in a couple of weeks (my mat leave actually ended on December 6th so been on normal annual leave since then) however I’ve just found out I’m pregnant again so will be wanting to leave work again around early august time I think. I’ve been worrying that my boss will have a paddy because I won’t be back in the office for long. Especially since the girl covering my mat leave has also just left to have a baby 🙈 is there anything I should worry about? Do I leave it a while before saying anything? Am I likely to be sacked? 😬😬