Ok, so I am going to be brutally honest here, and hope that you respect my honesty and don't think that I'm a bitter jerk. I fully admit that I have a double standard when it comes to pregnant people.
When someone tells me (or posts) that they are pregnant, my first genuine thought is "I am so happy for you!" I am actually happy for people who can have babies when they want to. However, my thoughts then tend to shift to feelings of sadness, jealousy, hope, or even anger. It all depends on who you are. If you are someone who I am very close to, I will feel mostly happy for you and a little sad for me, regardless of the circumstances. If you are someone who I am not as close to, it really depends on the circumstance. Let me elaborate. (Note: please do not try to figure out if you are one of the hypothetical people below. I mushed a whole bunch of different scenarios together for most.)
Pregnant Person A: Best friend, pregnant with another child. First thoughts: Wow, I am so happy for you, that is awesome! Second thoughts: Wow, it must be nice to be so fertile. Third thoughts: Crap. So much for being pregnant at the same time in our lifetimes. Fourth thoughts: More cute children to adore! Fifth thoughts: I am never going to be able to have a cohesive phone conversation with you again now that there are so many miniature people to get into the car, keep occupied, keep fed and dry and burped, keep from killing each other in the playroom. Overall thought: I am really happy for this person, even though they were able to get pregnant multiple times easily. But I am stuck with a tiny, petulant "Why not me?" voice in the back of my head that I can beat into submission most of the time.
Pregnant Person B: Facebook friend, haven't seen in person in a long time. Announces pregnancy via early ultrasound (so early it's just a gestational sac, no fetus to behold). Fleeting feelings of "I'm so happy for you!" that morph into incredible sadness and resentfulness that for some people, announcing a pregnancy so early is not a harbinger of doom and gloom--they can announce that way (some even by posting a pee stick picture, talk about early!) and have a healthy baby 9 months later. Must be nice to live in a fertile bubble where once you're pregnant, easily and quickly, you stay that way with little to no incident.
Pregnant Person C: Acquaintance, find out on Facebook (everyone's doing it apparently). Feel the "I'm so happy!" vibe and then actually talk to person or partner. Person/partner is totally unenthusiastic about having another baby (or a surprise baby, or another surprise baby). Sudden feelings of wanting to shoot pee sticks through this person's skull, because they could at least pretend to be happy that the miracle of life has visited them and not you, who would be totally grateful even if it meant living on the street. (I realize that different situations are difficult for different people, but that knee jerk feeling of "can't you just PRETEND to be happy???" supercedes any compassion for the added expense of a not totally planned baby).
Pregnant Person D: Person you overhear talking at work and then realize they're pregnant when they do nothing but complain about being pregnant or that instead of having a desperately wanted girl, ugh, they are having a boy. Or vice versa. I feel "wow, that's great she's pregnant" and then immediately want to inject progesterone in oil shots into this person's nether regions. The complaining about the downsides of pregnancy I can get behind--for some people it is not a glowy joyous time but a time filled with edema, painful varicose veins, hemorrhoids, and/or constant vomiting. I get that that sucks. But you get to have a baby at the end of it, so I can't help but not be too sympathetic. Especially if you know what I am going through and complain ad nauseum to me. The people who are not happy with the sex of the baby? I feel nothing but anger. It's not the baby store, people. You get to have a baby, and while you may be bummed that you didn't get your preference, you are pregnant with a beautiful child. The happiness feeling is short-lived in this case because the sense of injustice is just too overwhelming.
Pregnant Person E: Friend of any sort who had announced they were going to try to get pregnant soon, and then announce that they are pregnant fairly immediately after starting to try. I'm happy, really I am. But I am also very, very, very jealous. I do not wish my experience on anyone, but feel particularly gypped when someone is able to say "gee I'd like to have a baby right about now" and BAM! They are pregnant. I am happy for your incredible good luck. I am happy that your wish for family transformed itself instantly into expectant motherhood. I am just feeling like perhaps I built my house on an ancient burial ground or wronged some sorceress or some other scenario where I have really crap luck while you are probably not entirely aware of just how incredibly, beautifully fortunate you are.
Pregnant Person F: Person you know from treatment, clinic, fertility yoga class, or who you just know went through some fertility issues tells you they are pregnant. Instantaneous "I am SO HAPPY for you!" that stays and is followed by a surge of hope. Because if it happened for them, it can happen for you. Especially if the person had a particularly long and arduous journey. For me, and forgive me for this but I'm being honest here, this person EARNED it. They struggled for their baby and it finally happened. There may be a fleeting "When will it be my turn" that is simply human, but in general, this pregnant announcement gets hugs, jumping up and down, and tears of joy not tears of unfairness, jealousy, and bitter sadness.
I could keep going (there are SO many different scenarios!), but I won't. A couple things to add though--if you are lucky enough to be a pregnant person coming to tell me in whatever way that you are knocked up, PLEASE do not tell me in an apology. Do not tell me as you would tell an ex-lover that you probably gave them an STD. You are pregnant, and that is awesome. If you tell me like an apology I will feel worse. It is possible to desperately want what you've got and be happy for you. This is happy news, exciting news! I will feel like a killjoy of the worst sort if you tell me like it's bad news. I may be sad later, but my first thought is always well wishing. Because I am genuinely happy that this miracle happened to you (even if later I want to harm you with infertility paraphernalia due to witting or unwitting insensitivity). And someday I want to be announcing my pregnancy too. Just not with an ultrasound on Facebook, or a picture of my pee-soaked stick (let's face it, I won't have one to share anyway), or a transcript of the IVF nurse's message on my cell phone. And I won't be announcing early, because I don't live in a fertile bubble and am too afraid of tempting fate.
If, in the euphoria of my pregnant bliss I forget all this and turn into one of the more distressing pregnant people listed above, please feel free to whack me over the head with my sharps container.