What to say in a birthday card to recently bereaved

In a similar situation, I did as others have suggested, and bought a low key card which said " It's your birthday" ( no happy, celebrate,etc) and wrote in it that I knew that the day would be bittersweet, and that I was thinking of them.

Thinking of you today on your birthday, sending love and kind thoughts.

Perhaps something along the lines of "I know that this birthday may be a difficult one for you, and I wanted to let you know that I was thinking of you today."

What I did in a similar situation was to buy a blank card and I wrote "Thinking of you on your birthday" inside. I then added a personal note expressing my sympathy etc.

Just write 'with all my love'.

Just a ‘thinking of you’ card It won’t be a happy birthday will it? so don’t wish her one but she needs to know you haven’t forgotten her

A few years ago I was bereaved of my adult son.
People were thoughtful with my birthday cards some months later.
They choose cards which didn't say "Happy Birthday". Inside they wrote such things as, Thinking of you on your birthday and wishing you a gentle day.
It means a lot, still to receive birthday cards and kind wishes, whilst knowing that friends and family are aware of my feelings.
I wish your friend/family member
A gentle day.

Rather than send a birthday card I’d send a “Thinking of You” style of card.

A friend of mine recently lost her husband the day before her birthday. I just wrote that I couldn't imagine how she must be feeling, but didn't want the day to pass without her knowing she was in my thoughts - something to that effect.