Nifedifine taken for irritable uterus and contractions during pregnancy causes low blood pressure. Please help.

Hello doctor,

I am a 34-year-old woman who is currently 23 weeks pregnant. I have a history of an irritable uterus, which I experienced during my previous pregnancy as well. In that previous pregnancy, I successfully reached full term with the help of a cerclage and IV medication. However, in my current pregnancy, I do not have a cerclage, and my doctor has prescribed oral Progesterone as part of the management plan. Recently, I have been experiencing frequent contractions, occurring every five minutes and lasting one minute each. While they are not particularly painful and are similar to what I had in my previous pregnancy, I am concerned because I do not have a cerclage this time. My doctor has prescribed Nifedipine 20 mg slow-release tablets for me to take as needed to manage these contractions. Although I have not taken one yet, I am considering doing so now. I am currently taking Progesterone micronized 200 mg twice daily. However, I am a bit apprehensive because I have noticed that my blood pressure readings have been relatively low, ranging from 92 to 99/53 to 60 mm per Hg, as measured over several days. I would like to know if it is safe to take Nifedipine with this blood pressure. Unfortunately, my doctor is currently on vacation and has not responded to my messages. Kindly help.

Thank you doctor for the prompt reply,

I will consider using progesterone vaginally, even though it has caused vaginal irritation in the past. My cervical length was measured at 1.6 inches one week ago, but since then, I have experienced more contractions. I plan to explore the option of injection containing Hydroxyprogesterone and will consult my doctor when I can reach them. Currently, I am following modified bed rest and refraining from intercourse, and I spend most of the day lying on my left side. Regarding Nifedipine, I understand that it is generally safe to take as long as my systolic blood pressure is consistently above 90 before taking a tablet. However, if my systolic blood pressure drops to a range of 82 to 85 after taking it, I am uncertain whether this is normal or acceptable. I will reach out to my doctor for guidance in this situation. Thank you.

Hello doctor,

I am now 25 weeks pregnant and five days ago my cervix was measured transabdominally and it was 1.69 inches. In these last five days I have been in the process of moving to a new home and I have been quite stressed. My irritable uterus had more contractions than usual, most of them weak and long-lasting (uterus was semi-hard and sometimes lasting more than one to two minutes) and around five to six per day which were more intense (the whole uterus became rock hard for 30 seconds or so). I also started having some unpleasant pains in my lower abdomen, similar to menstruation or perhaps diarrhea. These pains continue even when there is no contraction and the uterus feel soft and elastic to touch. I did try Nifedipine and it is working but only for about four hours then the aches and mild contractions return. Today the uterus feels mostly soft but I am getting this feeling of pressure in my rectum. Like needing to have bowel movement but I do not actually need to. I already had one in the morning and this pressure started afterwards. My questions are:

1. Is it possible to enter preterm labor with aches or pressure feeling but a normal and soft uterus?

2. Do I need to feel the uterus being hard for this to happen? (considering my cervix is not incompetent, as it does not seem to be).

3. Can the pressure in the rectum be from something other than the cervix shortening or opening?

4. How much Nifedipine can I take daily? One per day does not seem nearly enough since it is effective for only four hours. On a positive note, it does not lower my blood pressure at all. My BP is steady at 95 to 97/55 to 60 mm of Hg with or without it.

Thank you so much.