(Closed) Low BMI affecting your change of getting pregnant?

posted 8 years ago in TTC
Post # 3
2538 posts
Sugar bee
  • Wedding: November 2009

Your doctor will know best but it seems that the effects with weight are exponential.  Like if you gain 10, you will have a large effect even if it doesn’t get your BMI over 20.  The same has gone for people losing weight. 

Good luck!

Post # 4
6291 posts
Bee Keeper
  • Wedding: August 2014

I personally wouldn’t worry. Usually, a low weight will affect fertility if it’s low enough to cause issues like amennorhea (absent periods); if you have a regular cycle and are otherwise healthy, I would not be stressing at this point about gaining weight. It is also important to remember that the BMI system is only a guide, and not everyone fits neatly into it. For example, I am currently just within the healthy BMI range for my height; but my diet is awful, and I look overweight for me; I don’t look fat, but I definitely do not suit the weight I am currently. I have a very small and petite bone structure, and am much healthier at a weight of 1-1.5 stone below what I am currently, which puts me in the ‘underweight’ category.

Bottom line, if you have a regular cycle and are ovulating, and are otherwise healthy, I would not be getting too caught up in your weight at this stage. But if you are concerned, speak to your doctor for advice.

Post # 5
1137 posts
Bumble bee
  • Wedding: September 2010

I have a very low BMI and my Dr isn’t worried about my fertility. My Dr said that a naturally low BMI due to high metabolism is rarely something to worry about. Most women who have fertility issues due to low BMI have gotten that way by non-normal means (eating disorder, obsessive exercising…etc) or by other medical issues (thyroid, hormones), which are the underlying cause of the infertility, the BMI is merely a symptom.

Additionally, he warned me against putting on “fat” to bring up my weight. He said this is equally as unhealthy as being unnaturally underweight. Fat will do nothing but clog your arteries and damage your heart. The only healthy way to put on weight is to increase muscle tone.

Post # 6
2000 posts
Buzzing bee
  • Wedding: July 2009

I know that Mrs. Quiche was advised to put on a couple pounds to aid her fertility (she’s said that on the TTC boards before). Not sure about the chances of it affecting conception, though. Best wishes and baby dust! 

Post # 7
830 posts
Busy bee
  • Wedding: July 2011

@StaceyA: You are just like me! I’m the same height as you and before having my daughter I weighed about 110. I’ve always been tiny, very small bones and overall frame. The most I weighed when not pregnant was about 115 and that’s when I was hitting the gym hard 5x a week, doing toning, lifting weights, protein shakes etc. It was a lot of upkeep and the second I stopped that routine my weight dropped back down. I prefer healthy foods so this may contribute but I think I just have a really high metabolism. I’m healthy overall. 

I had no issues getting pregnant, I actually got pregnant while on the pill. I had no issues during my pregnancy, I didn’t gain a lot of weight, under 20 lb. My breasts grew and I had a baby bump, no change in body appearance whatsoever other than that. My daughter was a healthy weight (right under 7 lb) and born on time. Since I barely gained any weight, I looked exactly the same within 2 days of giving birth except a much larger chest. 

I did have issues losing more weight after that, I think because breast feeding burns so many calories and I was just so busy, working and taking care of a baby. My daughter is about 2.5 now and I’m still about 5 lb under my normal weight. I blame this on a combination of my breasts shrinking 2 cup sizes from what they were pre pregnancy after I was done breast feeding and that I’ve also never gotten back into a regular work out routine except for occasional lifting of some hand weights. 

However I look healthy, no ribs or bones showing, just tiny. I’m not worried about it and I don’t see myself having any issues when we decide to concieve again. As long as you’re just naturally small and it’s not due to any health issues I’m sure you’ll be just fine. One of my friends is about 95 lb and she’s had 2 healthy boys with no issues whatsoever. I would recommend bulking up again before you TTC though in case you get morning sickness which will cause you to drop weight fast. Not fun when you’re already tiny. 

Post # 9
9028 posts
Buzzing Beekeeper
  • Wedding: June 2011

I’m skinny and even at 23 months pregnant I’m only 152 and 5ft 11 which means  I’m still in the normal BMI range for a non pregnant person. I didnt have any problems getting pregnant and my OB hasnt been worried about my weight at all. Being skinny doesn automatically mean you will have issues

Post # 10
1109 posts
Bumble bee
  • Wedding: September 2011

It sounds like your body likes to hang out at that weight naturally, which means it’s probably a perfectly healthy weight for you. BMI’s aren’t a perfect science, I wouldn’t stress out over trying to gain weight until you’ve tried to conceive. Trust your body, it knows what it’s doing 🙂

Post # 11
358 posts
Helper bee
  • Wedding: April 2013

I have a low BMI as well and have never had trouble conceiving. . Like others said, your doctor knows best. If your having a regular period and a regular flow I can’t see why you wouldn’t be able to conceive. Good Luck!

Post # 12
948 posts
Busy bee
  • Wedding: May 2019 - Coyaba Resort, Montego Bay

Bunny is right – my OB suggested that gaining weight might help us conceive. I am 6′ tall & have a really low BMI & since they couldn’t find anything else “wrong” with me, this was suggested.  I gained around 15 pounds over the course of 5 months or so in (what I think is) a healthy way & we shall see if it helped or not soon!

It wasn’t suggested because of an eating disorder or other illness, just that thin women can have a harder time getting pregnant (according to my doc & sister).

Post # 13
5147 posts
Bee Keeper
  • Wedding: June 2011

I have a low BMI (5’8″, 115 pounds). I just got pregnant on our 3rd month of trying. My sister is the same size as me, she has 2 kids, the first she got pregnant on birth control, the second she got pregnant 2 weeks after stopping birth control. My mom was also very thin when both my sister and I were concieved.

I think the people with low BMIs that have trouble getting pregnant are when they are unhealthy low BMIs, like extreme dieting or malnurishing themselves.

Some people are just genetically thinner than the average, and if you are healthy I don’t think it lowers your chances of conceiving.

Post # 14
772 posts
Busy bee
  • Wedding: December 2011

BMI is also only a guide.  It doesn’t always calculate out well for certain types of body shapes.  Like other bees have said, as long as you don’t have a history of eating disorder or other health related complications that keep your weight low, I wouldn’t worry.  


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